An International Olympic Committee member agreed to help a fake bid to bring the 2012 Olympics to London for cash, the BBC's Panorama reports.
Bulgarian Ivan Slavkov was secretly filmed by the television programme discussing how the votes of other IOC members could be "bought".
Four sports agents are also filmed saying they can secure nearly half the total votes needed, for a fee.
The IOC has launched an inquiry into the claims, aired on Wednesday.
IOC president Jacques Rogge promised to take the "necessary action" after the organisation's ethics committee had investigated the claims made in the programme.
IOC rules forbid committee members from being "involved with firms or persons whose activity is inconsistent with the principles set out in the Olympic charter".
But Professor Slavkov talked openly to New London Ventures - a fake company set up by Panorama - about the "favours" which could sway the voting.
The company is in no way connected to the official London 2012 bid, a fact made clear to all parties approached.
Professor Slavkov told Panorama he was "open to negotiations" about which way he was going to vote in the race to stage the games.
And different IOC members would want different things in order to vote, he said, such as business contracts.
The meeting was set up by Goran Takac, one of four sports agents featured in the programme who specialises in helping cities win the Olympics.
Panorama reporters posed as consultants acting for clients with business interests in east London who wanted the Games to come to the city.
They met four agents who said they could secure a total of 54 votes - nine short of the 63 required to host the Olympics.
Mr Takac named more than 30 IOC members who he said he could approach to negotiate backing for London.
About one member, he said: "He loves Paris but needs money."
Bulgarian Ivan Slavkov was secretly filmed by Panorama
Mr Takac said he could probably get 15 to 20 votes, of which half would require "payment".
An IOC spokesman said the matter had been referred to its Ethics Commission and Panorama has said it will discuss with them how it can help with the inquiry.
Meanwhile, Mike Lee, director of communications and public affairs at London 2012, said his bid team was not accused of any wrongdoing.
He said: "We understand that certain allegations are made as a result of the programme's undercover operation but they are not in any way connected with the London bid.
"Seb Coe has emphasised that this bid is being conducted in an ethical and proper manner and within the bidding rules set by the International Olympic Committee.
"There is nothing in this programme which brings that into question.
"Panorama's wider allegations regarding the bidding process have already been referred to the IOC's Ethics Commission and these matters will be dealt with by the IOC in due course."
When approached by the programme, Mr Takac said he had known Panorama's story was fake and had simply played along.
He said that both he and Professor Slavkov had only agreed to the meeting because they wanted to expose what they thought was a real attempt at corruption.
Professor Slavkov added that he had deliberately hinted that his vote could be swayed in order to trap the Panorama team.
He said: "Whatever I could say during the meeting was intended to trap the 'corruptors'."
IOC president Jacques Rogge promised to eliminate corruption following the 1998 Salt Lake City scandal in which 13 Olympic officials were accused of accepting bribes.
The Ethics Commission was set up as part of the reforms introduced in the wake of that crisis.
London is up against Paris, Madrid, New York and Moscow for the right to stage the 2012 Games.