London - Marks & Spencer's chief finance officer Alan Stewart on Thursday quit to join Tesco, leaving one struggling British retail giant for another.

A source familiar with the situation said Stewart had already left Marks & Spencer but was unlikely to start work at Tesco before the end of this year due to a six-month notice period and a non-compete clause in his contract.

Tesco has been looking for a new finance chief since Laurie McIlwee announced his intention to quit in April.

His appointment will be a boost to Tesco chief executive Philip Clarke, who is currently the only executive on Tesco's board, and who is facing questions over whether he has the right strategy to turn around the 95-year-old group.

Stewart has held the CFO role at M&S since October 2010 and had property added to his role less than two weeks ago when Chief Executive Marc Bolland shuffled the responsibilities of his executive team.

Stewart is a former finance director of WH Smith and has also held executive roles at HSBC and Thomas Cook.

He leaves Bolland, who is also struggling against tough trading and who on Tuesday was criticised by private shareholders at the firm's annual investor meeting. - Reuters