MOSCOW, March 6 (R-Sport) - The state-run construction company set up to build most of the facilities for the 2014 Sochi Winter Olympics has been accused by Russian auditors of unjustified cost inflations to the tune of $506 million.

Fears of the corruption potential from Russia's first-ever Winter Games were exacerbated earlier this year, when organizers announced costs had ballooned to $50 billion, making them the most expensive Olympics ever.

Now Olympstroi, which is building the entire coastal cluster of facilities and some in the mountains above Sochi, has been criticized for deliberately understating the expected costs.

"An investigation has shown that corporation executives created the conditions for an unjustified increase in the estimated cost of the sports facilities checked by the Audit Chamber," a chamber report circulated in the upper house of parliament on Wednesday read.

"In total, the rise in costs of the sports facilities is 15.5 billion rubles ($500 million)," the report said.

It mentioned the Sanki Sliding Center bobsled and luge track, the Bolshoi Ice Arena for the men's hockey tournament and "other" facilities.

The report claimed that Olympstroi executives have "taken decisions that increased the cost of facilities without providing any grounds whatsoever for the new calculations, or they were presented without sufficient motivation."

The Audit Chamber recommended the government re-evaluate the cost of each facility that underwent checks.