Banks are under new pressure to reveal the true scale of cyberfraud affecting their customers.

The chairman of the Commons Treasury Committee, Andrew Tyrie, has written to all big five banking groups calling for greater transparency.

Mr Tyrie, a Conservative, moved after his committee last month heard evidence that half of all cybercrime affecting bank customers went unreported.

In letters to Royal Bank of Scotland, Lloyds, HSBC, Barclays and Santander, he said that it was important that banks collated and reported the total value of accounts at risk of fraud.

Currently institutions only report sums that are irretrievable.

The MP said: ??Banks are perhaps understandably reticent about disclosing information that could be used by fraudsters.

"But the public and consumer interest in a high level of transparency is also strong."