The theft of personnel records through the UK government's tax credit computer system may be worse than first suspected, officials have admitted.

Last week, the Department for Work and Pensions (DWP) said around 1,500 employees may have been compromised, but that figure is now believed to be higher, said a spokeswoman. The theft was discovered during compliance checks and resulted in the tax credit website being taken down.

About 13,000 people worked for the service throughout the UK at the time of the theft, and investigators are trying to determine whose identities were taken, the DWP said. There is no evidence the agency's IT systems were breached but could not comment further on how the information was stored. DWP has its own special powers to conduct criminal investigations,.

The information is being used in attempts to wrongfully claim tax credits from the Revenue.