The Apprentice boss Lord Sugar has denied that his abrasive style amounts to bullying contestants on the BBC1 show.

The new series of The Apprentice begins later this month, with Lord Sugar returning alongside his no-nonsense sidekicks Karren Brady and Nick Hewer.

Lord Sugar, 67, has famously given some of the show's failing contestants a dressing down over the years, but the tycoon insisted that he was not being cruel.

"They've not just arrived from the planet Mars. They know what they are letting themselves in for," he told Radio Times magazine.

"They haven't been banged up in some Siberian prison somewhere. I make it perfectly clear to them when I see them for the first time in the boardroom that if you can't stand the heat, get out of the kitchen - it is as simple as that."

He dismissed the suggestion that he was plain-speaking to the point of being bullying, saying: "You have to look at my history.

"People would have reported it if lots of people were taking me to tribunals. Speak to my employees. I've got people here who have worked for me for 35 to 40 years. They work for me because they enjoy working for me."

"We don't bully people here and I'm not getting involved in discussing that with you."

The multi-millionaire added: "It is not bullying to speak your mind. I don't flower my words. If someone is useless, I'll tell them. If someone has done a good job, I'll also tell them.

"Identifying a truth is not bullying... No one likes to be told a home truth."

The tycoon told the magazine that he often tells contestants "in a very nice way" that they are not ready for the show but that "there are others who both I and the audience are very annoyed with, and who perhaps deserve a bit of bringing down to earth."

Some former candidates, such as Katie Hopkins, who joined I'm A Celebrity... Get Me Out Of Here! and Luisa Zissman, who appeared on Celebrity Big Brother, have chased the spotlight since their time on The Apprentice.

Lord Sugar criticised former contestants who want fame, saying: "They'd go to the opening of an envelope if they got an invitation.

"They have their Andy Warhol moment, thinking it's going to make them famous, but very few have actually succeeded. Before long they're of no interest to anybody."

Previous winners have included last year's victor Leah Totton, who set up a cosmetic clinic with Lord Sugar, as well as Tom Pellereau, who enjoyed success with his curved nail file, and Lee McQueen, who rang in sick on his first day in the new £100,000 job and no longer works for the tycoon.

Last year Stella English, who won the 2010 series, lost her claim of constructive dismissal against Lord Sugar.

The businessman, famous for telling candidates "You're fired!", defended his record with past winners, saying. "The last three candidates are in business with me and they're doing very, very well. Some of the others worked for me for a couple of years and they've gone on to work in other things."

The tycoon, who displays on his wall cheques that he has presented to the taxman, said that he was proud to pay his taxes.

"I could have sodded off to Monte Carlo or the Bahamas but we paid the money in cold blood," he said.

"You've got to pay tax, it is as simple as that. I don't want to live a life dodging taxmen.

"I could have put my money in tax-avoidance schemes or hedge funds, but the only hedge fund I've ever invested in is a Black and Decker."

Series seven winner Pellereau said that despite his huge success with his nail care products, Lord Sugar "can still be pretty hard on me".

"The other day I presented what I thought was a brilliant idea to him in a board meeting and he thought I was joking. He said: 'Are you mad? This is utter rubbish!'," he told the magazine.

Dr Totton, who set up a cosmetic clinic with Lord Sugar, admitted that the multi-millionaire had turned down her offers to give him Botox.

Meanwhile, Tre Azam, from series three, complained: "During filming, we were told we'd be taken for dinner and get to sit with him. I thought this would be a great opportunity to ask him questions and learn from him."

Azam, who was convicted in 2008 of falsely claiming housing benefits, added: "But he spent the entire time telling us how much money he'd made and how many planes he's got."

These are the 20 candidates hoping to land Lord Sugar's backing - and avoid a sacking - as they competing in the new series of The Apprentice:

:: Scott McCulloch, 24, East Kilbride

Clinical development strategist

Scott started out with a recruitment company after leaving school and is now responsible for global strategic partnerships between clinical development companies. He has previously travelled the world to work with emerging markets in business development for clinical research. Scott says he is determined, trustworthy and hungry to succeed. He admires the brands Pfizer and GSK, and businessmen such as Peter Jones.

He said: "From the minute I wake up to the minute I go to sleep, making money and conducting business is on my mind."

:: Bianca Miller, 25, London

Owns a branding company

After university, Bianca joined a major management and technology consulting firm as a human resources advisor, before launching her own business at the age of 23. Her branding company, The Be Group, was named as one of the Startups 100 businesses of 2013. Bianca calls herself determined, ambitious and pedantic.

She said: "I regret not becoming a scientist so I could clone myself and be more successful in half the time."

:: Ella Jade Bitton, 23, Hertfordshire

Business management graduate

Ella's first job was working as a fashion studio assistant for designer Jonathan Saunders. At 16, she negotiated an interior design concession stand in Harrods for her family business. Since leaving university, she has been responsible for the marketing strategy and online presence of her family's interior design company.

She said: "The future belongs to those who believe in the beauty of their dreams."

:: Jemma Bird, 26, West Midlands

Operations manager

Jemma rates Simon Cowell as a role model. She is a trained dancer and dance teacher and passionate about the arts. Her proudest business achievement to date has been founding an entertainment cabaret agency, for which she scouts performers, sources bookings, produces performances and markets the business.

She said: "I'm always the girl that nearly wins, I'm hoping this time it will be different."

:: Katie Bulmer-Cooke, 27, Sunderland

Fitness entrepreneur

Katie has won several awards for her work as a personal trainer. She creates and markets her own work-out programmes and DVDs and has been a health and fitness expert for Argos. She would describe herself as honest, down-to-earth and energetic.

She said: "In business I'm like a little stealth bomber that flies under the radar and smashes the competition before they've even realised I'm here."

:: Lauren Riley, 28, London

Solicitor

As a family solicitor, Lauren specialises in family law, including divorce, separation, finances and property, and says she is passionate about achieving fair outcomes for her clients. She says she is outgoing and ambitious, and wishes that she had had the idea for Facebook.

She said: "I'm absolutely not a shrinking violet. I'm very known for speaking my own mind."

:: Lindsay Booth, 29, Leicester

Owner, Aquatic Swimming Academy

A swimming instructor for 14 years, Lindsay is the founder of a swimming academy, which has taught hundreds of children over the past four years. She would describe herself as compassionate and ambitious.

She said: "The other candidates will underestimate how feisty I am, and how I will fight and prove that I can get to the end."

:: Nurun Ahmed, 36, Peterborough

Marketing officer and fashion retailer

As well as working full-time as a marketing officer, Nurun runs three businesses. She says she is thoughtful, considerate and a multi-tasker. Her proudest business achievement is setting up three small businesses within 18 months.

She said: "I'm the type of person that doesn't take five hours to do one job, I do 20 jobs in five hours."

:: Pamela Uddin, 23, Dublin

Assistant brand manager

After graduating from university with first class honours, Pamela won a scholarship to complete her masters in international business. Since leaving university, she has worked in brand marketing. She would describe herself as logical, charismatic and a good decision maker, but admits she can talk too much.

She said: "I am street and people savvy as well as being business savvy."

:: Roisin Hogan, 32, Dublin

Accountant

A chartered accountant, Roisin is following her dream to start her own business. She says she is confident, driven and creative, and being a risk taker has also made her a keen poker player in her spare time.

She said: "Manipulate, persuade and conquer. I would identify my opponent's weaknesses and pick them off one by one."

:: Sarah Dales, 32, London

Former PA and hypnotherapist

Sarah works as an executive assistant for a top financial firm, and previously worked at Goldman Sachs, while also running her own hypnotherapy and match-making businesses. She describes herself as hard-working, positive and tenacious, though she can repeat herself if she feels she is not being listened to. Her proudest business achievement is setting up her hypnotherapy practice on Harley Street.

She said: "I am the pioneer and the ground breaker, and I possess all the talents to succeed."

:: Chiles Cartwright, 35, Shropshire

Company director

Chiles owns a consultancy business and a building materials supplier, and before that he worked in management for international consumer brands for nine years. He describes himself as self-motivated, loyal and committed to everything he does. Chiles also has a passion for martial arts and is a black belt in karate.

He said: "I consider myself one of the most credible candidates in this process. I don't believe that anyone has the wealth and breadth of business acumen that I've gained over the years."

:: Daniel Lassman, 27, Essex

Director of a pub quiz company

Daniel used to be a footballer before running his own pub quiz company - he had a year's contract with Hornchurch FC, but it was not renewed when he got injured. He has also worked as a market trader in his family business. He says James Caan is an inspiration to him in business because of his calm and collected manner.

He said: " I will out-sell them, I will out-class them and I will perform the best just by being me."

:: Felipe Alviar-Baquero, 33, Kent

Lawyer

Columbian-born Felipe works as a solicitor at an international law firm and was named one of the Top 100 Columbians in 2012, the same year that he was an Olympic torchbearer. Felipe describes his biggest business achievement as designing and launching a children's play area. He is passionate about social entrepreneurship and is a trustee for a British charity supporting vulnerable children in Colombia.

He said: "I studied law because I wanted to change the world. But my real passion is business."

:: James Hill, 26, Chesterfield

Owner of multiple businesses

James got his start in business when he set up a hand car wash, and has since launched other businesses including supplying gaming machines to bars and clubs in the UK and Ireland, and opening a restaurant and bar. He says he is enthusiastic and energetic with a drive to succeed, but admits that he can be a bit of a know-it-all.

He said: "Me and Lord Sugar could build an empire together. I think I am him when he was my age."

:: Mark Wright, 24, London

Digital marketing sales manager

Australian-born Mark has been recognised repeatedly for the highest revenue growth in his company, where he supports internet marketing consultants. He has been working in sales for the digital health and fitness industries for nine years and his first job was washing cars for his dad's business. Mark says he is easy to talk to, orgnaised and ambitious. He names his business inspirations as John D Rockefeller, Andrew Carnegie and JP Morgan as they are all entrepreneurs who have built their own empires.

He said: "I'm very, very aggressive. I will not leave the room without getting a sale."

:: Robert Goodwin, 25, East Sussex

Marketing manager

Robert is responsible for the global marketing of an international brand in sports nutrition and has managed a campaign for the company's largest ever advertising spend. His early jobs included being a tennis coach when he was 15 and working in his uncle's art shop. Robert says he feels inspired by Harry Selfridge for creating market-leading retail services and brands such as Net-A-Porter for their luxurious, aspirational qualities.

He said: "I'm fearless and if I don't shut up about something, you should just trust it's a well thought out decision."

:: Sanjay Sood-Smith, 27, London

Banking senior manager

Sanjay is responsible for the online sales strategy of three national banking brands and previously worked as a bank manager who improved the ranking of his branch from the 900s to 30th in the space of six months. He was put in charge of 14 London retail branches because of his success. Sanjay describes himself as practical, enthusiastic and generous, but says he can worry too much.

He said: "If I had to choose between friendship and profit I'd choose profit. I'm not in this process to make friends with people, I'm here to win."

:: Solomon Akhtar, 22, London

Technology entrepreneur

Solomon works at a creative agency, but also runs his own company, a social media technology business. He has created and managed student events before, including a shop lock-in and group yacht trip around Croatia. He calls himself enthusiastic, energetic, personable and passionate about technology and travel.

He said: "I am from the 'ideas generation'; because of my age, I understand technology and how to turn it into a business."

:: Steven Ugoalah, 25, London

Social worker

Canadian Steven spent a year travelling the Arctic for a community development social work project with remote Inuit communities. He now lives in London, running his own social work consultancy as well as managing a property portfolio. Steven says he is resourceful, dynamic and a great negotiator, but admits he often becomes frustrated when people do not have the same high standards as him.

He said: "I can deliver in minus 50, I can deliver in plus 10. If we went to Mars right now, I'd find a way to be excellent."