(ShareCast News) - Ex-Tesco chief executive Philip Clarke has been called in for questioning by the Serious Fraud Office over the £326m accounting irregularities that emerged in the company's accounts soon after he left.Clarke has been requisitioned, according to sources cited by Bloomberg, and will be interviewed under caution, along with his former head of UK operations, Chris Bush, and commercial director, Kevin Grace.This follows the SFO's similar quizzing of finance director Carl Rogberg, after the independent government department began investigating last October how the FTSE 100 supermarket group came to overstate its profits by £250m.Clarke was given the boot in July 2014, after three years at the top of a company he joined as a boy, with the scandal coming to light two months later thanks to a whistleblower in the accounts department, with the figure since upgraded to £326m.In May, Tesco said it will look to recover Clarke's £1.2m pay-off if evidence proves the supermarket guilty of gross misconduct under his leadership.Several legal claims by shareholders in the UK and US were also launched as a result of the profit mis-statement, seeking compensation from the supermarket chain after the scandal triggered a run on the company's shares.The SFO has said it expected the investigation to be completed by the end of the year, with speculation that the prosecutor may settle with the company using a US-style non-prosecution agreement.