A CONSERVATIVE Cabinet ­minister has called for a crackdown on the number of controversial zero-hours contracts given to workers.

Work and Pensions Secretary Iain Duncan Smith said he personally felt far fewer jobs should offer employees no guarantee of work or pay.

Reports suggest up to one million workers could be employed on the terms. They leave staff tied to a company but with no guarantee of their working hours, and nullify their wider employment rights.

Thousands of workers at high street names such as Sports Direct and McDonalds as well as in the public sector are on the contracts.

The Tory-LibDem Coalition also employs almost 150 Whitehall staff on zero-hours contracts.

In a little-noticed answer to an MP last month, Mr Duncan Smith said: "Personally, I think there should be far fewer zero-hours contracts."

He added: "We are trying to work with employers and the Department for Business, Innovation and Skills (BIS) to persuade those who have a genuine long-term job to get off zero-hours contracts and get a proper contract of work."

He also suggested that the contracts could play havoc with his upcoming Universal Credit system, under which benefits payments will alter depending on how much a claimant earns.

A spokesman for BIS, which is carrying out a review into the issue, denied the department was trying to persuade employers or employees to dump the contracts.

He said: "All that we are doing at the moment is trying to gather evidence as to how these contracts are working in practice.

"Officials are working on that at the moment and will report to the Secretary of State in September.

"He will then decide the next steps to take".

Business Secretary Vince Cable has ruled out banning the contracts altogether and said that for many workers they are "not a problem" .

However, he has suggested that it could be wrong for companies to demand an exclusive relationship with staff unless they can offer them stable employment.

Mr Cable is expected to decide in September whether or not to hold a formal consultation on specific proposals to alter the terms of such contracts.

A Labour source accused the Coalition of being all over the place on zero-hours contracts.

He added: "This week we found out that one million people are on zero hours contracts in the UK.

"The Government urgently needs to get to grips with what it is doing to sort this issue out."

Business leaders have defended the use of the contracts, saying they can provide workers with much needed flexibility.

However, opponents warn they can leave staff exploited and trapped - forced to be constantly available with no guarantee of work.

Meanwhile, trade unions warn that while jobless figures are falling they mask a rise in the use of the contracts across a number of sectors.

A report by the Chartered ­Institute of Personnel and Development earlier this week estimated up to one million workers are on the deals, compared to the official figure of 250,000.