A Morrisons employee has been arrested in the wake of a major breach of staff payroll data at the retailer.

This morning’s arrest follows a joint investigation carried out with West Yorkshire Police.

On Friday last week it emerged that confidential payroll data including the bank account details of some 100,000 staff had been stolen from the retailer’s IT system. The data appeared on a file-sharing site based in the US, which has not been named in light of an ongoing investigation.

The retailer was informed of the theft after a disc containing the data was sent to the Telegraph and Argus, a local newspaper in Bradford where Morrisons has its head office. The newspaper did not publish the data.

It is understood that the employee, who has not been named, has been arrested on suspicion of two offences, one relating to the Fraud Act and the other under the Computer Misuse Act.

A Morrisons spokesman said that there had been “no reports of unusual activity” on any staff members’ bank accounts and that there was a “low risk” posed by the breach as only account numbers and sort codes were revealed.

The data leak crisis comes at a bad time for boss Dalton Philips, who on Thursday revealed massive losses at Morrisons as well as a huge profit warning for its current year.

Morrisons has said that it is working with staff members over concerns about their bank account details and other data loss, and has purchased support from Experian to manage anti-fraud measures in the wake of the breach.