(Reuters) — Banks are under no obligation to reimburse the tens of thousands of people who have lost money totaling hundreds of millions of pounds (dollars) by making transfers from their bank accounts to fraudsters, a British regulator ruled on Friday.

The Payment Systems Regulator, part of the Financial Conduct Authority (FCA), was responding to a complaint from consumer rights campaign group Which? about authorized "push" payments or APP.

APP scams involve bank customers being tricked by phone or email into transferring money to a person or organization they believe to be legitimate.

Which? has argued that banks should reimburse such transfers in the same way as they already do for scams involving direct debit, credit and debit card payments and fraudulent account activity.

However, the Payment Systems Regulator said there was insufficient evidence to force banks to reimburse APP payments, although it will consider whether it should propose changes as more evidence emerges.

"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," Hannah Nixon, managing director of the Payment Systems Regulator, said.

"Tens of thousands of people have, combined, lost hundreds of millions of pounds to these scams, but the data we have seen so far is incomplete. We need a concerted and coordinated industry-wide approach to better protect consumers, and we need it to start today."

Which? said the regulator had let banks off the hook by failing to address the issue of liability.

"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," said Alex Neill, managing director of Which?

The Payment Systems Regulator announced a package of measures to reduce fraudsters' ability to carry out scams and, when they do occur, to increase the chances of recovering the money.

It has asked the industry to develop a way of legally sharing information to help victims recover their money.

"We look forward to working with all parties ... to help develop a common understanding of what can and cannot be shared under existing legislation and then develop actions needed to change that legislation if necessary," the Financial Fraud Action U.K. payments industry association said.

The sector is also being told to develop, collect and publish "robust" statistics on scams.

Christopher Woolard, executive director of strategy and competition at the FCA, which also received the Which? complaint, said the FCA would address any "firm-specific" issues directly, and take further action if needed.