Some employees are paid £2,000 a day
The pay rates of around 3,000 contract staff of RBS were leaked after an email accidently got sent to employees of RBS.
Some of the employees are paid £2,000 a day, according to a report by SearchSecurity.
According to the report, a staff member of employment agency Hays sent the email containing day rates paid to contractors to 800 RBS employees.
Hays has a contract with RBS to supply temporary staff.
RBS has said that no customer details had been breached. It has not commented on the agreement with Hays following the incident.
The bank said: "We are extremely disappointed that confidential personnel data has been shared by one of our suppliers. This is unacceptable and we are taking action to address this issue. No customer information has been compromised."
Hays has apologised for the error.
"The data included the roles and the pay rates of certain contractors, but did not include any bank account details or national insurance numbers," a company statement said.
"Hays recognises that the correct treatment of data is of the utmost importance and has apologised to RBS for this error. We are taking the unauthorised release of this data extremely seriously and are working with RBS to recover the data from recipients where possible."