The plot was exposed when New Jersey police found computer discs containing customer records at the home of a man under investigation for other alleged offences. Police have since charged nine people, including seven bank staff, in connection with the data theft, which is thought to have involved customers of Wachovia, Bank of America, PNC Bank, and Commerce Bank.

Up to 14,000 Wachovia customer account names were found on the seized discs, along with the details of 75 Bank of America customers and about 15 at PNC Bank.

The bank employees allegedly sold screen shots of individual financial records for $10 a pop. These were then sold on to collection agencies for up to $100 per account.

The banks are monitoring the accounts for evidence of suspicious activity and have awarded affected customers a year's free subscription to a credit reporting service.