Mr Mandelson is alleged to have warned Tory frontbenchers, including Francis Maude, the spokesman for culture, at a private meeting last week that the financial success of the project was "on a knife-edge" and would be undermined by continued Tory sniping.
He attempted to secure Tory support in advance of the unveiling tomorrow by Tony Blair of the detailed plans for the Dome in an attempt to overcome the criticism.
Although the project has the backing of Michael Heseltine, the former deputy prime minister who is on the project team, Mr Maude hit back last night by accusing Mr Mandelson of not telling the truth, and calling for him to be sacked as the minister for the Dome.
Ministers are concerned about complaints from the public that the money would be better spent in reducing the record waiting lists for treatment on the National Health Service, which is celebrating its 50th anniversary this year.
But the Tories made clear that there will be no truce. Mr Maude said the Millennium Dome was intended to be "a new Labour monument", which the Tories suspect is being used to boost Labour's re-election chances. He said there could be Tory support, if Mr Blair agreed to the Dome being opened with William Hague, the Tory leader. That offer is likely to be dismissed out of hand by the Prime Minister, but Mr Maude's claims infuriated ministers.
He said: "When is Peter Mandelson telling the truth? Was he telling us the truth at our meeting on Tuesday when he described the Millennium Dome project as 'on a knife-edge' because he couldn't secure the necessary sponsorship, or was he telling the truth when only a few hours later he announced that he had 'no worries' about its sponsorship?' "
Mr Mandelson, whose reputation is resting on the success of the Dome, told The Independent that the Dome would be a success, and it could be sold after the year-long "experience" exhibition.
He has been approached by two organisations who want to take over the Dome after the year-long show was over, but he was also interested in the idea by Tony Banks, the sports minister, for turning it into a football stadium for the London bid for the Olympics.
Mr Mandelson also said on the BBC Breakfast with Frost programme that he could cut the cost to the National Lottery millennium fund, which is paying pounds 400m towards the cost of the centre in south-east London. He said he hoped the gate receipts would be higher than expected from the estimated 12 million visitors in the first year, enabling more money to be repaid to the millennium fund.Reuse content