The UK Information Commissioner's Office (ICO) is investigating claims that financial data - including private account numbers, PINs and security codes - of tens of thousands of UK customers is available for sale on the Internet.
The data protection watchdog has launched an investigation following a report by UK newspaper The Times which uncovered more than 100 Web sites that are trafficking British bank details. Scotland Yard is reported to be looking into the matter.
Times reporters managed to download the banking information of 32 people for free and also found a fraudster offering to sell 30,000 UK credit card numbers for less than £1 each.
A spokesman for Information Commissioner Richard Thomas told The Times that the office will be looking at the evidence provided and investigating the circumstances.
He said the ICO can take action against UK-based organisations that flout the Data Protection Act. In cases where Web sites are not UK-based the ICO will work with counterparts in the relevant country.
Later this week Thomas is set to address the Commons Justice Committee on the additional powers needed to prevent data breaches.