The new chief executive of Tesco is to start today after the company altered its financial expectations from £2.4 billion from £2.8 billion, its third profit warning of 2014.

The new boss, Dave Lewis, was rushed in a month ahead of schedule to start immediately on a new turnaround plan for the business.

Sir Richard Broadbent, Tesco's chairman, said Lewis's review would consider "all options that create value for customers and shareholders". He said: "The board's priority is to improve the performance of the group. We have taken prudent and decisive action solely to that end."