The organisers of the 2016 Rio Olympics have denied that vote buying helped to secure the games.
French newspaper Le Monde has reported that a company linked to Brazilian businessman Arthur Cesar de Menezes Soares Filho paid $1.5 million to Papa Massata Diack, the son of Lamine Diack, the then-president of the International Association of Athletics Federations (IAAF) three days before a 2009 decision on the host city for the 2016 Games.
Rio lost the first vote to Madrid but bounced back to win the nomination on a third ballot, by 66 votes to 32.
Le Monde said Papa Massata Diack had also paid almost $300,000 to prominent IOC member Frankie Fredericks.
Fredericks said he has done nothing wrong and that the money was for "services rendered" to promote the sport in Africa.
The IOC said on Friday that its commission has started investigating the claims.
"The IOC remains fully committed to clarifying this situation, working in cooperation with the (French) prosecutor," the organisation said in a statement.
A spokesman for the Rio 2016 Games said the allegations did not affect the choice made by IOC delegates to award the Games to Rio.
"Rio's victory was very clear," Mario Andrada said.
"The French investigation concerns six members of the IOC and six members would not have changed the result at all. The vote was clean."
Le Monde said that three days before the October 2009 vote in Copenhagen, Pamodzi Consulting, a company owned by Papa Massata Diack received the $1.5 million payment from Matlock Capital Group, a holding company based in the British Virgin Islands.
Diack, whose father Lamine is currently awaiting trial in France on aggravated money laundering and corruption charges, also received $500,000 from Matlock Capital Group through a Russian bank account, Le Monde said.
Papa Massata Diack was banned for life from athletics last year over multi-million dollar corruption claims.
Le Monde said Papa Massata Diack transferred almost $300,000 to a company linked to Fredericks, a multiple Olympic and world medallist over 100 and 200m.
Fredericks, now a member of the IAAF's ruling Council, told Le Monde the money was paid for work he did to promote athletics in Africa between 2007 and 2011.
"The payment has nothing whatsoever to do with the Olympic Games and I was not an IAAF board member at the time and did not breach any regulation or rule of ethics," he told Le Monde.
The IOC said: "As far as Mr Fredericks is concerned, he informed the IOC and explained the situation and emphasised his innocence immediately upon being contacted by the journalist.
"The IOC trusts that Mr Fredericks will bring all the elements to prove his innocence against these allegations made by Le Monde.
"Immediately after a link was made between this contractual payment and the vote for the host city of the Olympic Games 2016, Mr Fredericks himself also turned to the IOC Ethics Commission which is now following up on all the allegations in order to fully clarify this matter."
Andrada said the ongoing investigation by French authorities was focused on Lamine Diack and did not have any connection with Rio's candidacy.
"The Rio Games have already taken place and filled Brazilians with pride, and only when the French have concluded their investigation will it be possible to say who are the beneficiaries of this scheme," he said.
"Already, however, it's clear that the Rio Games have nothing to do with this."
Rio became the first South American city to host the Olympic games in August.
Despite concerns over the city's ability to host the Games during Brazil's worst recession, the Olympics were held without any major problems. However, many of the venues and installations have since been abandoned.