Sources have suggested that M&S chief executive Stuart Rose has been in talks with Green, a friend and former colleague, for several months.
The loss of Green would be a bitter blow to Tesco chief executive Sir Terry Leahy. In November Green set out ambitious plans for Tesco to topple high street fashion giants M&S, Next and Topshop. He said that Tesco would invest millions of pounds in an expanded range of upmarket clothing.