A union today pressed Royal Bank of Scotland to explain its use of contractors after a recruitment agency mistakenly emailed the details of hefty pay packets for thousands of temporary staff.

Unite has expressed 'serious concerns' over the revelations, inadvertently exposed by an employee of Hays, which are understood to show temporary staff receiving up to £2,000 sterling a day - equivalent to £500,000 a year.

Some 3,000 contractors' names and billing rates were mistakenly attached to an email sent from Hays to 800 RBS staff which was supposed to remind managers to complete timesheets before the bank holiday weekend.

The insight into contractors' wages is likely to provoke outrage as RBS is not only 83% owned by the state but in the process of cutting thousands of permanent staff jobs.

'It is wholly inappropriate that RBS, backed by UK taxpayers, appears to be throwing money at thousands of contractors, the United union said.

RBS, which owns Ulster Bank here, said it was 'disappointed' by the incident, while Hays said it had apologised to the bank for the error and has launched an investigation.

RBS said this month around 2,000 jobs would go at its investment banking arm in the next 12 to 18 months as it unveiled a half-year loss of £794m. The bank's share price has also fallen to 20 pence - less than half the 50 pence price tag paid by the UK government for its stake.

It is understood temporary staff work in divisions ranging from human resources to risk management, while the highest-earning contractors have specialist accounting, financial and IT expertise.

Unite said contractors should not be used as a short term fix and the bank should focus on investing in staff.

