The Government this week launched an investigation into high street banks and threatened to toughen the existing Banking Code of Practice after complaints that some institutions are failing to deal openly with their customers.

Helen Liddell, Economic Secretary to the Treasury, said she was "extremely concerned" about claims that some banks are not telling their customers about different accounts.

The probe also follows angry protests from clients of Northern Rock, the former building society, who claim they have been switched between accounts without their consent.