UK Internet bank Cahoot was forced to shut down yesterday after the discovery of a major security breach which allowed customers to access other people's accounts without using a password, according to a report by the BBC.
The BBC says it was contacted by a viewer who found he could log in to other people's Cahoot accounts using just a user name and bypassing any security questions.
Cahoot, which is run by Abbey, says the problem was caused by a system upgrade 12 days ago. The site was closed down for 10 hours on Thursday to carry out repairs.
The bank apologised for the breach, but insisted that hackers would not have been able to move money between accounts.
Tim Sawyer, head of Cahoot, admitted that the online bank needed to learn lessons from the security breach and review its procedures.
"I believe that we need to look closely at our processes because this has not been our greatest moment," he told the BBC.