The president of the Russian Olympic Committee has brushed off questions about corruption allegations that have dogged the upcoming Winter Games in Sochi.

Asked about allegations of stolen money and inflated building contracts, Alexander Zhukov said they had no basis in reality.

But critics say that corruption is behind the massive cost of these Winter Olympics, which has ballooned to $51 billion.

Anti-corruption groups believe that Russian President Vladimir Putin’s childhood friends and other allies were awarded inflated contracts to build the infrastructure needed to support the Games.

“His cronies, when they understood that it was so important for him politically, they understood that they could charge whatever they want,” said Vladimir Ashurkov, the head of an anti-corruption foundation.

Putin’s friends include Russian Railways boss Vladimir Yakunin, whose job was to build a modern train service that connects the two Olympic sites. The cost of that project is more than $8.5 billion – more than the entire cost of 2010 Winter Olympics in Vancouver.

In another example, the initial estimate for the cost of the Olympic stadium in Sochi was $50 million. The final cost is now estimated to be between $500 and $700 million.

A Russian anti-corruption activist has launched an interactive website, Sochi.FBK.info, detailing cost overruns and conflicts of interest.

Alexei Navalny claims that Russia spent twice as much as necessary to build at least 10 of the Olympic venues in Sochi.

The Sochi Games will be the most expensive Olympics in history, but Russian officials insist that the $51 billion price tag is misleading.

They say that only a small chunk is directly related to the Olympics and that the rest has gone to infrastructure projects the state would have carried out anyway.

Putin himself has denied the corruption allegations, saying that investors initially underestimated the costs of Olympics projects.

On Tuesday, Putin thanked the International Olympic Committee for having faith in Sochi, a city that had barely 15 per cent of the needed infrastructure before construction work began.

Putin said that Sochi is now more beautiful and more comfortable.

IOC President Thomas Bach said the committee can see that “Russia, and the Russians, have delivered.”

With a report from CTV’s Daniele Hamamdjian and files from The Associated Press