UK watchdog to probe Tesco errors

London - Britain's Serious Fraud Office (SFO) is to launch a formal criminal probe into accounting errors at troubled supermarket Tesco, Sky News reported on Wednesday.

Britain's biggest retailer, which has suffered a string of recent profit warnings and management exits, is already being investigated by accounting watchdog, the Financial Reporting Council, after the firm overstated first-half profits by £250m.

Tesco, whose shares slipped half a percent on the news, declined to comment.

A SFO spokesperson said it was still doing a preliminary investigation of Tesco but declined to say whether it had launched a full probe. "When we do have something to announce in terms of a next stage, that will be announced," he said.