All bank staff are to be trained to spot signs that a customer may be withdrawing cash to give to a scammer.

Police hope the scheme will help reduce financial crime by spotting scams before money has been handed over.

The plan is to train every single front-facing employee of banks, building societies and Post Offices.

Cash payments to fraudsters are typically much harder to trace than online payments with the vast majority of cases going unsolved.

Typical frauds of this kind include paying rogue builders, romance scams and elderly abuse.

'It just didn't add up'

Staff at one bank which has trialled the scheme helped stop a customer being swindled out of £13,000.

Ray, who is in his 60s, was approached by a builder at his home in London about some work on his house.

He had withdrawn £6,000 from his local branch after explaining to staff what it was going to be used for.

But when he returned a week later to take out another £13,000 he was recognised by staff member Ann-Marie.

She asked him questions about his cash withdrawal which raised suspicions.

Ray handed over the flier he had been given with the builder's contact details and staff gave him a call.

Ann-Marie added: "The person that answered wasn't very professional and the alarm bells started to ring. Plus the amount he [Ray] wanted to cash and the work he needed done just didn't add up."

Staff contacted the police who visited Ray the next day when the builder was at his property.

Officers did a background check on the builder and which uncovered suspicious activity and he was arrested.

The new scheme, known as the Banking Protocol, is aimed at ensuring banks and police are more active in protecting customers.

It is being run as a joint venture between the police, Financial Fraud Action - which represents banks - and National Trading Standards.

All customer-facing bank staff will be told to look out for specific signs that a client may be the victim of ongoing fraud.

If they have suspicions, they are encouraged to call the police and give a special password.

Sixteen arrests

Police trained under the protocol will also commit to investigating the fraud as a priority - often visiting the bank branch, or the customer's home, immediately.

In some cases, they may be able to catch the criminal waiting outside the bank or the victim's home to collect the cash.

Bank staff taking part in the trial scheme in London made 178 calls to police which resulted in 16 arrests.

Banks say £1.4m has already been stopped from leaving customer accounts.

Police, Financial Fraud Action and National Trading Standards have hailed the trial a success.

The scheme is expected to begin in the next few weeks with the first 16 police forces trained by the end of June.