Steve Back is to be replaced as chief executive of Somerfield by former Asda chief Paul Mason on March 6.

Back has resigned with immediate effect and John Lovering, Somerfield chairman, has assumed the role of executive chairman until Mason takes over.

Mason has just quit jeans brand Levi Strauss after running its European business for the last two years. Before that he was boss of Matalan.

The supermarket chain was taken over by a consortium of bidders led by Iranian property magnate Robert Tchenguiz in December.

The new owners were said to be unhappy with Back’s performance, according to press reports.

Back joined Somerfield as finance director in November 2002, becoming chief executive in September 2004.