The organisers of the 2012 London Olympics insist the city won the right to host the Games ''fairly and squarely'' after suggestions a potentially decisive vote was cast in error by an International Olympic Committee delegate.

Senior IOC official Alex Gilady has told of his fears that Greek delegate Lambis Nikolaou may have voted for Paris in the third round by mistake, which he claims had the effect of eliminating Madrid, rather than Paris, from the final round.

The Israeli contended that Paris' backers would then have switched to Madrid for the final round, making the Spanish capital victorious.

British Olympic officials seem unperturbed by Gilady's remarks, and a spokeswoman for the London Organising Committee for the Olympic Games (LOCOG) said: ''There are lots of folklore stories about who voted for whom, but the vote was a secret ballot. Speculating on voting processes in a secret ballot is pointless.

''This is the opinion of one individual and we are not going to get drawn into any further speculation.

''The story is irrelevant, what matters is that London won the right to host the Games fairly and squarely and we look forward to hosting the best Games ever in 2012.''

Steve Cram, a former 1,500 metres world record holder and ambassador for the London bid, said: ''If anyone made a mistake it should have been brought to light at the time. This is a pointless exercise.

''Like everyone else I watched how the voting worked on TV and it seemed to have been done very efficiently.''

A senior International Association of Athletics Federation source admitted there were rumours in Singapore that one of the IOC members had voted late, possibly in the third round.

''If that was the case Madrid and Paris would have had 32 votes each but that was not taken into account,'' said the source, who was present in Singapore.

''But I must stress, although it has been talked about, everything is based upon a rumour.''

A spokesman for the IOC said: ''The IOC does not comment on the voting intentions of its membership.''

The spokesman added that there were currently no plans to review the voting system ahead of the ballot for the 2016 Games.

IOC member Craig Reedie, the former chairman of the British Olympic Association, dismissed the matter out of hand, saying: ''The story is totally irrelevant, the voting was conducted in a secret ballot under the rules of the IOC, absolutely properly, all votes were properly recorded.

''If Alex is claiming that an unnamed member 'might' have done something which 'might' have brought about something else which 'might' have brought about a different voting structure, then I'm afraid this is the kind of tittle-tattle that happens after many an IOC vote.

''London won the Games hands down. If you're looking for reasons for London's win I suspect you should probably look at the quality of the bidding effort that went in in Singapore, the quality of the lobbying effort and, above all, the quality of the presentation.''

Referring to the third round of the voting exchanges in Singapore in July, Gilady said: ''London was ahead, but Paris and Madrid were 33-31 in the votes.

''Let's say what we think now happened, that one member made a mistake and voted for Paris rather than Madrid.

''If he had voted for Madrid it would be 32-32. We would have to have had a vote-off.

''In the vote-off all the votes supporting London would go to Madrid, because the fear was that Paris had a big chance to win.''

Gilady claimed that all the votes from an eliminated Paris would then have gone to support Madrid in the final.

In the final round of voting, London beat Paris 54-50 to win the right to host the 2012 Olympics.

Feliciano Maroyal, the chief executive officer for the Madrid 2012 bid, which would have succeeded if Gilady's analysis is correct, said: ''We were very close to winning. We can never know if the Greek vote would have been decisive, but it is lamentable for one human error to have ruined all our hard work which we put in trying to win the Games.''

Prime Minister Tony Blair said: ''If we had been left in with Spain it would have been tougher because I think we got some of the South American vote which came to us rather than Paris."