Ministers will be quizzed in parliament next week

The government expects to sign a contract at the end of February with Legacy, which has bid �125m for the Dome and wants to turn it into a high-tech business park.

But news of the donation follows criticism of Labour over party funding after its attempts earlier last week to keep private millionaire publisher Paul Hamlyn's donation of �2m.

The Conservatives say they will question the donations in parliament next week.

A spokesman for Legacy said Mr Bourne had promised Labour the �100,000 donation in three instalments three years ago, long before any bid for the Dome had even been considered.

He added: "It was almost like a direct debit. If you had asked Labour three years ago whether they were expecting �33,000 from Mr Bourne in late 2000, they would have said they were.

What Robert does with his own personal money is nothing to do with Legacy

Legacy spokesman

"It had absolutely nothing to do with the Dome deal."

He added: "What Robert does with his own personal money is nothing to do with Legacy.

"It is nothing to do with the bid and nothing to do with the deal."

Mr Bourne - a long-time Labour donor - donated the �33,000 late last year.

He had no current plans to make further personal donations to Labour, but had not ruled out possible future donations, said the spokesman.

While Legacy is the current preferred bidder for the attraction, it lost out to Japan's Nomura in the initial bidding contest but benefited when Nomura pulled out.

Cabinet Office Minister Lord Falconer, who has responsibility for the Dome, said: "The idea that we are negotiating the sale with Legacy because Robert Bourne has given money to the Labour Party is just wrong.

"When Nomura pulled out last September, it was entirely sensible and proper that we should have discussions with the runner-up, Legacy."

Doubts over Legacy bid

With the prospect of a General Election this spring, Labour will be glad of all donations.

But senior backbenchers are said to be concerned that the party may be tainted by accusations of impropriety.

Last week the government was reportedly told that the plans of its preferred Dome bidder would fail.

The Times said there was growing pessimism within the Millennium Commission about the viability of Legacy's proposal.

And Dome chief executive Pierre-Yves Gerbeau has said he is still interested in heading a bid to continue its use as a visitor attraction.

The contents of the Dome, including turnstiles, hi-tech lighting and sound equipment, will be auctioned between 27 February and 2 March in a sale that could yield up to �10m.