Royal Bank of Scotland (RBS) is axing 1,000 technology jobs as part of a cull of 3,500 positions across the company.
The Unite union says RBS plans to offshore upwards of 500 technology roles to its existing IT operations in the US, India and the Far East.
The other jobs will be lost from the Business Services Operations department.
Rob MacGregor, Unite national officer said, "The news that The Royal Bank of Scotland is to cut another 3,500 staff from across the UK is a horror story.
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"It will be a specially bitter pill for staff to swallow as RBS has decided to move some of the jobs abroad to the Far East, India and America."
Twelve UK centres are being closed and a further three centres are under review.
One-third of all the losses, about 1,500 roles, are attributable to the divestment to Santander of 318 bank branches, as ordered by the European Commission.
It is not the first round of job-cuts for the company, which reduced its headcount by thousands last year.