The Payments Systems Regulator (PSR) has urged banks to step up measures to tackle scams in which people are conned into transferring money to a fraudster.
The watchdog's recommendation came in response to a "super complaint" from consumer group Which?, which highlighted the increasing number of so-called "push" frauds, which involves fraudster tricking their victims into disclosing their bank details.
"The regulator has finally acknowledged the considerable consumer harm caused by bank transfer scams," said Alex Neill, managing director of Which? home and legal services.
"However, while recognising that the industry is not doing enough, it has failed to adequately address the issue of liability and has let the banks off the hook, giving them little incentive to do more to protect their customers.
"The outcome for people is unfortunately that they will continue to be scammed out of millions of pounds. We need to see swift action and not see this kicked into the long grass in the second half of 2017."
The consumer group made the complaint in September, arguing a number of people were being conned into transferring were "often large and can be life-changing". Which? explained the scams would either involve getting fraudulent access to a customer's bank account or tricking users into authorising a fraudulent payment.
Cooperation among lenders could be crucial to detect fraudulent transactions, the regulator said, adding there was more banks could to identify potentially suspicious payments.
"In a short space of time we have built a clearer picture of the problems we are facing, and it is evident that this type of scam is a growing problem that needs to be tackled," said PSR's managing director, Hannah Nixon.
"Tens of thousands of people have, combined, lost hundreds of millions of pounds to these scams. We need a concerted and co-ordinated industry-wide approach to better protect consumers, and we need it to start today."
The PSR, however, stopped short of suggesting banks should shoulder the costs of compensating customers, although it added it will continue to monitor the issue.
"As work progresses and additional evidence comes to light, we will consider whether it is appropriate to propose changes to the obligations or incentives that banks have for these types of scams," it said in a statement.