Northern Rock, the nationalised mortgage lender has begun consultations with unions and staff over plans to shed 2,000 jobs.
Up to a third of 6,000 jobs across all levels of staff are to be axed by the end of 2011, however the bank suggested the bulk would be lost this year.
Trade union Unite called for any redundancies to be voluntary.
Unite deputy general secretary Graham Goddard said: “The workforce did not contribute to the situation which the bank now finds itself in and should not be expected to pay the ultimate price by being forced out of their jobs.
“Decisions must not be made merely in the pursuit of short-term cost savings,” he said.
Northern Rock was bailed out with £25bn in public money after running out of cash last September, before being nationalised in February.
Ron Sandler, chairman of Northern Rock, said: “This is a very difficult time for our people and we will continue to work closely with them and Unite, to minimise the extent and impact of potential job losses.”