Lloyds Banking Group came under attack for cutting hundreds more jobs and planning to close a large office.
The Unite union said 850 staff would be axed. It said the bank has announced almost 2,750 job losses since the start of the year.
Lloyds, HSBC and Barclays combined have announced cuts of around 5,500 jobs since the beginning of 2013, said Unite.
Unite National officer Dominic Hook said: "The constant job cuts across the banking industry is bad for bank staff, does nothing to support customers and it's bad for Britain's economy. Since January 5,500 job cuts have been announced by high street banks."
The bank said around 275 roles are being created, mainly in Belfast and Pitreavie, Scotland.
It said in a statement: "All affected employees have been briefed by their line manager today. The group's recognised unions were consulted prior to this announcement and will continue to be consulted.
"Where it is necessary for employees to leave the company, it will look to achieve this by offering voluntary redundancy. Compulsory redundancies will always be a last resort."