The World Anti-Doping Agency has added xenon gas to its list of banned substances after claims it can be used by athletes to help boost performance.

Scientific studies suggest that the gas artificially increases the levels of (EPO) in the blood, which is forbidden under WADA's rules.

In a statement Sunday, WADA said its executive committee approved the modification of its 2014 prohibited list to include xenon and the change should come into effect after a three-month notice period.

The WADA board also urged Spanish authorities to conclude the case of Operation Puerto as possible, saying the "lack of progress in the case was sending the wrong message to clean athletes right across the world"

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