A Morrisons employee has been arrested in connection with the allege theft of payroll data on the same day the supermarket issued a huge profit warning.
West Yorkshire police confirmed it arrested a man on suspicion of making or supplying an article for use in fraud. He remains in custody.
Morrisons said the data theft affected staff from all levels-including the board- but refused to comment on whether chief executive Dalton Philips was among them or how many of its 130,000 were affected.
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."
The theft involved information, including bank account details, relating to thousands of members of its staff and later published online on Thursday as the supermarket issued its second profit warning in two months, sending shares tumbling by 12 per cent.
A disc of the data was also sent anonymously to Yorkshire local newspaper, the Telegraph & Argus, by a "concerned Morrisons shopper".
Morrisons said it became aware of the theft last Thursday, shortly after it unveiled its latest set of results to the City, and the information was taken down immediately. Employees were emailed and informed by managers about the data theft.
Britain's fourth biggest supermarket said it is reviewing internal data security measures and it is working with Experian to detect misuse of information
In a statement, Morrisons said: "We can confirm there has been no loss of customer data and no colleague will be left financially disadvantaged."
The embarrassing theft comes at a challenging time for the supermarket as it battles super discounters Aldi and Lidl.