Updated

An interactive website launched Monday by anti-corruption activist Alexei Navalny paints a vivid picture of suspected cost overruns and conflicts of interest at the Sochi Winter Olympics.

Russia has spent about $51 billion to deliver the Olympics in Sochi, which run Feb. 7-23, making them the most expensive Olympics ever even though winter games have many fewer athletes competing than summer games do.

Navalny claims that Russia spent twice as much as necessary to build at least 10 of the Olympic venues — including the Bolshoi Ice Palace, the Fisht Stadium for the opening/closing ceremonies and the speed-skating arena.

Allegations of corruption have dogged preparations for the Sochi Games for years, as reported by The Associated Press and others. Navalny's new website — Sochi.FBK.info — combines data gathered during his own investigations along with media reports and other activists' analysis.

Using colorful graphics, the website makes a wide range of data accessible in English and Russian.

"Athletes are not the only people who compete in Sochi," Navalny, who finished a strong second in Moscow's mayoral election last year, wrote on the website. "Officials and businessmen also took part in the games and turned them into a source of income."

President Vladimir Putin has rejected claims about rampant corruption in Sochi, saying the inflated prices were due to the honest mistakes of investors who underestimated the costs.

"If anybody has got this information, please show this to us," Putin said in a recent television interview. "But so far we haven't seen anything except speculation."

A 2012 report by the government's Audit Chamber found about 15 billion rubles (about $500 million) in "unreasonable" cost overruns in the preparations for the Sochi Olympics.

Auditors found that the work of some staff members at Olympstroi, the state company in charge of Sochi construction, between 2008 and 2010 was "conducive to incurring unreasonable cost overruns." At least three criminal investigations against Olympstroi employees have been opened, but none of them has reached court. Olympstroi has since changed its management.

The Sochi Organizing Committee would not comment Monday on Navalny's new website.

Navalny does not seem to provide solid evidence of how money was stolen during the many Sochi construction projects. This has proven extremely difficult to do because the games were not covered by Russian laws on tenders and procurement, making officials unaccountable for the money spent.

Olympstroi was given free rein by Putin to "determine the ground rules for selecting investors and contractors" for Olympic venues. This created fertile ground for corruption in the allocation of funds, according to Ivan Ninenko, deputy director of Transparency International in Moscow.

Olympstroi "is even less transparent than companies in (Russia's) state-owned sector, where corruption is rife," he told the AP.

The total amount of state contracts overseen by Olympstroi was about 700 billion rubles, or $22 billon, according to Deputy Prime Minister Dmitry Kozak, the government official in charge of the games.

A website Navalny set up in 2010, called Rospil, has monitored thousands of Russian state contracts and appealed to law enforcement agencies to get the murky ones annulled. Rospil has been successful in overturning nearly 130 contracts worth nearly $2 billion in taxpayer money. Not for the Sochi Games, though.

"Opportunities for public control are very limited" for Sochi contracts, said Konstantin Kalmykov, who works for Navalny. All it takes is a presidential or government decree to award a contract to a specific firm.

"If there were regular public control in place, that would be a big factor in saving funds and increasing efficiency of spending," Kalmykov said.

Navalny's new website lists several Sochi construction projects with evident conflicts of interest. In one of the most glaring examples, the Ice Cube curling stadium was built by a company controlled by businessman Alexander Svishchev, the father of Dmitry Svishchev, president of the Russian curling federation, the website said, citing public records.

One of the key beneficiaries of lucrative Olympic contracts was Putin's childhood friend Arkady Rotenberg. Through a majority-owned subsidiary, Rotenberg holds nearly 39 percent of the Mostotrest company, which amassed a dozen Olympics-related state contracts to build nearly all of the highways in the area.

Mostotrest's contracts in Sochi amounted to $3.1 billion, including a $1.6 billion bypass for Sochi, as well as tunnels, bridges and railroads, the company confirmed to the AP.

The Russian business daily Vedomosti in 2009 analyzed scores of tenders for Olympic contracts and discovered that the majority of bids were very close to the maximum the state said it would pay, and in many cases bidders were barred from running, leaving one company to claim the contract.

Mostotrest won the $1.6 billion bypass contract after firms owned by tycoons Oleg Deripaska and Roman Abramovich dropped out of the competition in 2009. Mostotrest offered to build the road for 59.36 billion rubles, just barely below the maximum state price of 60.9 billion rubles.