A Morrisons employee has been arrested by police investigating the theft of payroll data from the supermarket firm relating to thousands of members of staff.
The theft involved information including bank account details and was published on a website.
West Yorkshire Police said it arrested a man today on suspicion of making or supplying an article for use in fraud.
Detective Chief Inspector Gary Hooks said: "An employee of Morrisons has been arrested in Leeds this morning in connection with an investigation into the theft of data from the company.
"He is currently in custody."
The theft was seen as a fresh blow to Morrisons, especially as it came a day after Britain's fourth biggest supermarket tumbled to a £176 million annual loss and issued a profits warning, sending shares down by 12%.
The company said the data theft affected staff from all levels of the organisation including the board, but would not comment on whether chief executive Dalton Philips was among them.
The supermarket said it became aware of the data theft on Thursday, hours after it announced financial results to the City and that Mr Philips was leading the response.
It wrote to all employees with an email address to inform them of the data theft, while managers were also informing workers at its sites.
Morrisons did not say how many of its 130,000 employees were affected.
The supermarket said in a statement last week that the data was also sent on a disc to a newspaper.
It said: "We can confirm there has been no loss of customer data and no colleague will be left financially disadvantaged."
The firm said it was urgently reviewing internal data security measures.