Fraud victims waste precious time waiting on hold when alerting their bank to a scam as criminals whisk away their savings in minutes, a new report has warned.

Consumer group Which? found some 15pc of victims waited more than 30 minutes trying to warn their bank that fraudsters had taken their money.

However, research by MasterCard in 2019 showed automated attacks using so-called mule accounts – those set up or hijacked to traffic stolen funds – could transfer money to multiple other accounts in a matter of minutes. The technique has made it hard, slow or impossible to recover funds, which are often sent abroad.

The survey also found a third of victims said their bank offered no advice on improving security. This is despite banks claiming to offer tips and support, suggesting many customers have found it hard to access, Which? said.

Jenny Ross, of the firm, said: "The lack of help provided to some victims of bank transfer scams is particularly concerning and protections for this type of fraud have to be strengthened. There must be a mandatory reimbursement scheme for all payment providers to ensure customers are treated fairly and consistently."

One woman spent seven hours on hold with HSBC trying to report a £3,900 fraud and racked up a £50 phone bill, Which? said.

Last year, £479m was lost to scammers who persuaded savers to send them money by posing as bank workers, government agencies and investment schemes, among other ploys. Less than half was refunded by banks.

UK Finance, the trade body for UK banks, conceded that there was more it could do but said the banking system needed help in fighting fraud from telecoms companies and internet providers.

A spokesman added: “Fraud has a devastating emotional impact on victims and the money stolen goes on to fund serious organised crime, so the banking industry's primary focus is on stopping these scams happening in the first place.

“A total of £188.3 million has been reimbursed to thousands of customers since a voluntary code was introduced in May 2019. However, we agree more needs to be done and we firmly believe that a regulated code, backed by legislation, is the most effective answer so that consumer protections apply consistently across the banking industry.”

A HSBC spokesman said: “We act with empathy and understanding when investigating a case and we work hard to ensure fair and reasonable outcomes for our customers, including providing them with appropriate information to help prevent future occurrences.”