Wealthy business people will refuse to donate to Labour for as long as Gordon Brown remains party leader, according to the chairman of the Labour Finance & Industry Group.

Peter Slowe, who heads the group – designed to build bridges between Labour and business – has called for Lord Mandelson to take over as prime minister. Mr Slowe, a lifelong party member, told the Financial Times that Mr Brown should step aside in the autumn to make way for the business secretary because Labour’s prospects were otherwise grim.