Ex-Tesco chief executive Sir Terry Leahy has said he is “shocked” at Tesco’s recent accounting crisis at a conference where he was also forced to defend the supermarket’s international expansion.

Speaking at an Evening Standard business conference, Leahy rejected accusations that Tesco became “too big” during his reign and said US subsidiary Fresh and Easy, which filed for bankruptcy last year, would have become a good business in time, the Guardian newspaper reported.

Although he wouldn’t comment further on the ongoing investigations into Tesco’s accounting black-hole, Leahy said new chief executive, Dave Lewis, should focus harder on meeting shoppers’ needs.

Leahy, who stepped down just over three years ago, was touted as the UK’s most successful businessman after turning Tesco into the world’s third-biggest retailer during his reign between 1997 and 2011.

Last month's accounting revelations led to the suspensions of several senior executives, and chairman Richard Broadbent stepping down.

A new chairman has not yet been announced, after one fancied candidate – chief executive of catering giant Compass Richard Cousins – ruled himself out on Wednesday, the paper said.

Cousins joined Tesco as a non-executive director last month.