The London 2012 bid team have defended themselves against any suggestion of corruption, insisting they are “as close to certain as possible” the right to host the Olympics in the capital was won cleanly.

Rio Games vote-winner questioned by police over ‘rigged bidding process’ Read more

A deepening of the bribery scandal engulfing the International Olympic Committee has led to questions about how the Sochi 2014, Rio 2016 and Tokyo 2020 Games were awarded. Sir Keith Mills, the former chief executive of London 2012, said he witnessed nothing untoward during 18 months of campaigning that culminated in London’s victory. “The IOC had a big problem in the late 1990s and as a result of that put in place some pretty draconian controls,” Mills said. “When we were bidding for London 2012 we couldn’t buy IOC members a coffee.”

The IOC introduced new rules for bidding cities after the discovery in 1998 of widespread bribery associated with Salt Lake City’s bid for the 2002 Winter Olympics. Ten IOC members were expelled or resigned as a result of the scandal.

“They were all so paranoid they would come under suspicion,” Mills said. “Whenever we met they made a big point of making sure it was in public and everything was seen to be above board. Whether that has evaporated over time I don’t know.”

Sebastian Coe, who led London’s bid, told the Guardian he was confident “nothing embarrassing” would be uncovered and his views were echoed by Craig Reedie, the former chairman of the British Olympic Association.

A joint investigation by Brazilian and French authorities this week led to the questioning of the Brazilian Olympic Committee president, Carlos Nuzman, a well-known figure in Olympic circles. The equivalent of £155,000 was said to have been found in his closet and seized during a raid on his home. Nuzman’s lawyer said on Tuesday that his client “did not commit any irregularity”.

Prosecutors suspect the former Olympic volleyball player facilitated payments of $2m made by a prominent Brazilian businessman into the account of Papa Masatta Diack. They have alleged the money was intended as a bribe for his father, Lamine Diack, an influential IOC member and then the president of athletics world governing body, the IAAF.

Questions about the London bid are unavoidable given Lord Coe’s closeness with Diack Sr, whom he referred to as his “spiritual leader” when he succeeded the Senegalese as the president of the IAAF.

Diack, an IOC member from 1991 to 2013, was instrumental in organising the African bloc of votes. Mills said Diack was soon determined as a lost cause in the 2012 bidding process, contested by London, Paris, Madrid, New York and Moscow. “We identified Lamine Diack as a Paris bid supporter, so frankly spent very little time with him,” Mills said. “Seb knew him through athletics but I certainly didn’t have any conversations with him.”

It is not known how Diack voted in the secret ballot, which was narrowly won by London in a run-off with Paris. The IOC will this month approve Paris and Los Angeles as the hosts of the 2024 and 2028 Olympics, respectively. The Guardian understands fresh information from the ongoing French and Brazilian investigations will only increase scrutiny on how voting has been conducted in the past.

Reedie, a former vice-president of the IOC and now the president of the World Anti-Doping Agency, said London was to his knowledge “a clean bid”.

“Seb and I agreed right at the start that it was going to be done properly,” he said, “because if anything was even remotely improper it would kill the whole image of the Olympic movement in this country and besides, we didn’t have any money anyway.

“I’m surprised at Nuzman’s links to everything that’s going on in Brazil,” he added, “My wife and I took him and his wife out to dinner in Singapore but that is it. I was never approached with any inducements and to my knowledge neither were Seb or Keith. I’m as close to certain as possible that London was a clean bid.”