This article is the subject of a legal complaint from Derek Simpson and Unite

One of the leaders of Britain’s biggest union has been accused of breaking election rules, an allegation that could have serious implications in the battle to gain control of the organisation.

Derek Simpson, a strong ally of Gordon Brown, is standing for re-election as leader of the Amicus half of Unite, with voting due to begin on Monday. The Times learnt that his main rival, Kevin Coyne, made a complaint after Mr Simpson sent a letter to a million Unite members this week saying that it was “vital that I, together with senior colleagues, am able to provide the continuity so necessary in these difficult times”.

Under Amicus rules, candidates cannot use union resources in their campaigns.

Mr Coyne said that the letter, which outlines Unite’s efforts to help its members during the recession, would have cost the union more than £250,000 in postage alone.

The union said that an independent commissioner had seen a draft of the letter before it was sent and rejected Mr Coyne’s complaint. It added that it was not appropriate to comment on the commissioner’s decision. Mr Coyne is now taking his complaint to the Certification Officer, the unions’ watchdog.

Electoral Reform Services, which runs union elections, says that the election will cost Unite about £500,000.

The election process is checked by a returning officer and a scrutineer chosen by the union, but all union elections are ultimately governed by the Certification Officer, who has the power to order a fresh election if any rules have been broken.

Mr Simpson, who is standing for only a year’s term, triggered the election after a legal challenge was made to his attempt to stay beyond his retirement age.

The controversy comes amid fears that the union, which negotiated a £6 million overdraft last year, is running out of money. A senior Labour figure familiar with the union was worried that it may be in difficulty. Unite said that it had not used any of the overdraft.

Unite has given £13.4 million to Labour since Mr Brown became Prime Minister, and was instrumental in saving the party from bankruptcy last year.

It has given guarantees that it will continue to fund the party but ministers fear that it will run out of cash, partly as a result of a bitter fight between its joint general secretaries, Tony Woodley and Mr Simpson.

Ian Gibson, Labour MP for Norwich North, said: “There needs to be a breath of fresh air. Someone needs to take a hold and provide inspiration to members, many of whom are going to suffer more and more in coming months.”

Coincidentally, Mr Simpson recently met union activists in a tour of the country. The union offered to reimburse travel expenses for those attending. A union spokesman said that the tour had been arranged before the ballot was called and was not intended to further Mr Simpson’s election campaign. A complaint was made but dismissed by the independent commissioner.

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