Charlie Whelan, Gordon Brown's former special adviser, last night dismissed as "rubbish" allegations that he bullied officials at his union, Unite, in a power struggle aimed at promoting Ed Balls to become the next Labour leader.
Mr Whelan, who remains close to the Prime Minister, is alleged by The Spectator magazine to be using his influence in the union as part of a plot to install the Schools Secretary, Mr Balls, another ally of Mr Brown, as Labour leader when Mr Brown steps down.
Mr Whelan, political director of Unite, said the reports under the headline, "The Man Who Killed New Labour", were "completely libellous". He added: "It's outrageous. I am very surprised The Speccie has published it."
The report claimed staff at the Unite union were "stunned by Mr Whelan's arrival, and those who regarded it as a Brownite coup d'etat had their fears confirmed when the union sent £5,000 to Ed Balls's re-election campaign".
The union, formed from the former Transport and General Workers' Union (TGWU) and Amicus in 2007, is the main financial backer for the Labour Party and has donated £11m over three years. The Tories claimed in March that it was parachuting 59 of its members into seats in time for the election. Downing Street subsequently intervened to stop the union parachuting more of its candidates into safe Labour seats.
Unite members standing for Parliament include the Labour Party treasurer, Jack Dromey, in Birmingham Erdington, and John Cryer in Leyton and Wanstead. Mr Cryer, a former MP, is alleged to have been one of the Unite officials who complained about Mr Whelan, but withdrew the allegations.