Its use is being looked at by the prohibitive list committee, who will decide whether to recommend it be put on the banned list next year.

That is despite World Anti-Doping Agency director general David Howman saying its use had been known for "years and years, before Athens 2004".

He told insidethegames the use of xenon gas had not been previously looked at because "it wasn't an issue that needed to be addressed".

An investigation by German broadcaster WDR has sparked WADA's own probe.

It claimed members of the Russian team at Sochi inhaled the "performance enhancing" gas and alleged top Russian athletes have used  xenon gas to improve their performance as far back as Athens 2004.

If the prohibitive list committee chooses to recommend it become a banned substance, it will be put on a draft list and go out to consultation.

The use of xenon gas is not, at present, prohibited by the World Anti-Doping Agency
©Getty Images



Any "urgent" findings that mean the process should be speeded up will be presented to the Executive Board when it meets next month.

The production of EPO in the body encourages the formation of red blood cells which improves performance, particularly in endurance events.

The head of Russia's Federal Biomedical Agency, Vladimir Uiba, indicated last month that Russian athletes may have been using xenon gas but claimed it was not illegal.

"It is possible that our sportsmen have been using xenon inhalators but there is nothing wrong with that," Uiba is reported to have told Russian news agencies.

No Russian athletes failed a drugs test during the Games, but biathlete Irina Starykh was dropped from the Russian team days before the start of the Olympics after she admitted using a banned substance.

The Russian team topped the medals table at the Sochi Olympics, with 13 gold, 11 silver and nine bronze – a considerable improvement on its Vancouver 2010 haul when it came away with three gold medals.