Last week the supermarket announced that its profits had been overstated by £263m.

That is up from an initial estimate last month of £250m.

The accountancy firm Deloitte last week completed its investigation into Tesco's misreported profits.

It found that they were overstated by £118m in the first half of this year, by £70m in the 2013-2014 financial year and by £75m before that.

Tesco had been doing deals with suppliers over promotions, which is commonplace for supermarkets.

But it appears Tesco had been booking returns from those promotions too early, while pushing back the costs.

Eight executives have been suspended since that practice was revealed.

Tesco has said there was no evidence of personal gain from the mis-statement.

The news of the investigation by the SFO was first reported by Sky News. Tesco and the SFO declined to comment.