The row overshadowed a charm offensive by British Prime Minister Tony Blair, who took advantage of French President Jacques Chirac not arriving in Singapore until Tuesday, to press London's case with the International Olympic Committee.

Paris, the front-runner from the outset, still remains the slight favourite for Wednesday's vote, although London is regarded as running a very close second. New York, Madrid and Moscow are the other cities in the running.

The London campaign ignited the row with their European rival when two advisers to the bid criticised Paris' Stade de France stadium in comments at a press conference that came dangerously close to breaching IOC rules.

"I think the Paris stadium is a wonderful stadium. I really like going there to watch rugby but unfortunately rugby is not part of the Olympics," said Rod Sheard, an architect who has worked on London's proposed stadium.

"There are fundamental compromises when you introduce other sports into an Olympic stadium, into an athletics stadium."

Jim Sloman, who was the chief operating officer for the Sydney 2000 Games and now advises the London team, said in response to a question on the Stade de France that there was no advantage in having a stadium already built.

"The one thing you do have with an existing stadium is that it has been built for football, it hasn't been built for athletics," he said.

"It still has sight line problems. The London stadium will be built specifically for athletics."

Under rules set down by the IOC's ethics commission, bid teams are not allowed to criticise rival cities.

Paris mayor Bertrand Delanoe responded to the criticism with some barbs of his own.

"I think that to deserve victory you have to respect the Olympic spirit and demonstrate fair play," he said when asked about the remarks, then emphasised that London did not even yet have an Olympic stadium.

"One good thing about the Stade de France is that it exists."

French Sports Minister Jean Francois Lamour also rejected suggestions the stadium would be too old in 2012. "It was 20 years ahead of its time when it was built and it is updated every year," he said.

The London campaign later tried to play down the controversy by pointing out that Sloman and Sheard were not officially linked to its bid, despite the pair making the comments at an official press conference for the British capital.

"Very few candidate cities have spoken about another candidate city at all. There is good spirit among the candidate cities, we get along very well," British Olympic Association chairman Craig Reedie said.

London mayor Ken Livingstone and Britain's culture minister, Tessa Jowell, who is in charge of the city's bid, shared the stage with Sloman and Sheard.

Although the French were clearly unhappy with the comments, the Paris bid said it would not lodge an official complaint with the IOC, and IOC President Jacques Rogge said no action would be taken.

"No one has gone over the line. If anyone had, I would have intervened," Rogge said.

Elsewhere the public relations campaign of all five cities' bids kicked into overdrive with Blair grabbing most of the headlines as he undertook a hectic series of meetings.

Blair refused to say which IOC members he had met, or even the number, because of campaigning rules, but his spokesman conceded later that he had "as packed a diary as I have seen" for the next 48 hours.

"The basis of the bid is the strength of the bid. What I can do is make it clear that the bid has complete and total political support," Blair told reporters during a brief break from his lobbying.

Among the sporting celebrities in Singapore to lobby for various cities are Australian swimming champion Ian Thorpe, and former Romanian gymnast queen Nadia Comaneci, who are both backing New York.

For Spain, football star Raul, cycling legend Miguel Indurain and basketballer Pau Gasol were all in town. At the national level, Spanish Queen Sofia was also already in Singapore while Prime Minister Jose Luis Rodriguez Zapatero was due to arrive on Tuesday.

English football captain David Beckham was expected to arrive in Singapore later Monday to lobby for London, as was New York's trump card, boxing great Muhammad Ali.

With US President George W. Bush not coming to Singapore, New York Senator and former first lady Hillary Rodham Clinton will provide her city's political muscle. Russian Prime Minister Mikhail Fradkov was also on his way for Moscow.