When businesswoman Emma Watson answered her home phone one morning, little did she the call would end up costing her more than £100,000.

A woman claiming to be from her bank NatWest’s fraud department told her that they had detected attempts to withdraw money from her account.

Watson was in the middle of setting up a nursery. “There was a lot of money in there and I wanted to safeguard it,” Watson said. “She sounded totally professional, saying all the right reassuring words and seemed to be compassionate for the situation. She knew my name and where I banked. I don’t give out my landline number to anyone and I didn’t think twice that she wasn’t who she said she was.”

In a series of phone calls Watson, who lives in London, was told her account had been hacked and duly followed the instructions of the woman – who had a Scottish accent – to transfer cash into ‘temporary accounts’ in her name until a new one could be set up. By the time she realised it was a fraud those accounts had been drained of £104,000.

The case has now been passed from London's Metropolitan Police to Police Scotland for investigation.

Watson is far from alone. Figures from Financial Fraud Action UK show the losses from online or phone banking scams where a fraudster gains access to an individual’s bank account totalled £165.8million in 2015 across the UK - an increase of around 60 per cent on the previous year.

Organised criminal gangs based in Scotland are targeting victims both north and south of the border.

Tony Blake, senior fraud prevention officer with the Dedicated Card and Payment Crime Unit, a UK-wide police unit which works with industry fraud investigators, said fraudsters were finding it increasingly difficult to attack banking systems directly due to improved security, but around 95 per cent of people who receive an unexpected phone call from their bank will not challenge its authenticity.

“The fraudsters are targeting the next best thing – get the customer to give me all the information I need to attack their accounts,” he said. “If someone rings up and says I am from the bank, most people will trust that.”

Blake said the fraudsters were crime groups and “very well organised”, and did not have to be part of the banking system to know what questions to ask.

“They seem to hit certain areas at certain times – there is definitely a Scottish angle to it and definitely groups based in Scotland,” he said. “That has been going on for some time and there are still groups based in Scotland, which aren’t just targeting Scotland and have links with organised groups elsewhere in the UK.”

He added: “You can never discount corruption within an organisation as being part of it, but I am not personally aware of someone on the inside of a bank who has been arrested in relation to these type of crimes.

“I know that people who have worked in banks and listened to these phone calls say they sound like they may have worked in a bank at one time. I have heard bank staff saying the fraudster would almost get a gold star for customer service the way they have dealt with that person.”

Blake said the banks were constantly trying to keep ahead of the criminals, with new methods such as introducing voice recognition technology to detect fraudsters trying to pose as customers. But he pointed out advances in banking systems to improve service for customers can also be exploited by the fraudsters.

"If I can send you money via my online banking and you can get it three seconds later that is great – but it is also great for the fraudster to transfer money around,” he said.

The so-called ‘vishing’ scam which Watson fell victim to in June last year exploited faster payment banking systems, where money can be instantly transferred using a sort code and account number, without having to have a correct payee name.

Her husband Alexander, who works in PR, is frustrated that more than one year on from the scam, no arrests have been made. The account had been targeted at a time when there was an unusually high balance, as a result of raising their mortgage to fund the building of a nursery school. He said had been told by police in London investigating the case that some kind of “bank insider” was involved, although it is unknown from which bank. He said: “The victims are by no means just elderly vulnerable people, they are bright, financially astute people who have been cleverly hoodwinked by scams where fraudsters know your details and know about the fast transfer system. It doesn’t seem to me the banks will do anything until they are liable for the money lost - they are saying it is the responsibility of us as we moved the money and therefore it is none of their problem.”

Consumer organisation Which? recently launched a campaign calling for the UK Government’s Joint Fraud Taskforce to review how businesses take responsibility when their customers are scammed. It said the onus should not be left on customers to protect themselves.

Which? executive director Richard Lloyd said: “When we know that even the savviest people can be scammed by fraudsters, it’s vital that everything possible is done by businesses to protect consumers.”

Asked to comment on the case, the Metropolitan Police in London said it had now been transferred to Police Scotland. A Police Scotland spokesman said: “There is an ongoing inquiry and we cannot comment further.”

The banks say they publish regular scam awareness advice, work hard to raise awareness of scams and advise they will never instruct a customer to transfer money from their account by email, phone, text or any other means.

A spokesman for NatWest said: “We are sorry to hear of the distress caused to our customer who was the victim of a vishing scam. We take our customer’s security very seriously and work closely with other banks to recover funds when a customer has been the victim of a scam. In this case we recovered some of the money.”

The Watsons got £30,000 of their money back, but had to rely on loans from friends to replace the lost money and enable the nursery to be built.

The business is now successfully up and running, but Emma Watson said the scam had left them with a mountain to climb. “We have ended up with lots of loans to pay back,” she said. "Obviously now I know this kind of things happens, but I didn't before - at that time it was quite a new scam. You can’t quite believe it. These people can’t just get away with it.”