Recruitment company Hays has mistakenly e-mailed the confidential pay details of thousands of temporary Royal Bank of Scotland staff to other contractors.
In a gaffe first reported by Sky News, a Hays staffer inadvertently forwarded an e-mail containing the pay details of around 3000 contractors to 800 of the temps.
The information, which covers people working in areas such as risk management and human resources, reveals some of the staff are being paid up to £2000 a day.
RBS has branded the leak "unacceptable" and says it is "taking action" while Hays has apologised and insisted that no bank account details or national insurance numbers were exposed.
The leak has been seized on by unions furious that RBS - which is majority owned by the tax payer - is paying out such large sums to contract workers while laying off thousands of permanent staff.
David Fleming, Unite national officer, Unite, says: "We have expressed to the bank our unhappiness that thousands of permanent staff are being sacked when contractor staff continue to work in other areas of the bank. Instead the bank should be investing in its staff through retraining and upskilling."