The supermarket chain has launched a review of the figures to find out why its first half profit prediction was so inflated.
Tesco has asked Deloitte to undertake an “independent and comprehensive” review, which it said involved the accelerated recognition of commercial income and delayed accrual of costs.
Dave Lewis, chief executive at Tesco for just three weeks, said: “We have uncovered a serious issue and responded accordingly.
“We will take decisive action as the results of the investigation become clear,” he said.
He added that a number of people have already been suspended from duty while the investigation is underway, including four senior executives, according to the BBC. UK managing director Chris Bush has been identified as one of those suspended.
Tesco said it discovered the overstatement of its figures, made as part of a 29 August profit warning, during its final preparations for its forthcoming interim results.