This is to be set at 150 nanograms per millilitre with immediate effect, compared with 15 ng/ml until now.

WADA said the change would mean that athletes using the substance in-competition would be detected.

It has never been prohibited out-of-competition.

WADA told insidethegames, nonetheless, that there was no guarantee that an athlete who used marijuana shortly before a competition would not test positive, since it might remain in their system for a longer period.

Word of the change emerged in a WADA statement released after the recent meetings in Montreal of the body's executive committee and Foundation Board.

These were said to have focused mainly on proposed amendments to a new World Anti-Doping Code.

Marijuana is included in the cannabinoid class of drugs, which accounted for 7.9 per cent of adverse analytical – and atypical – findings reported by accredited laboratories in 2011.

An article published on FIFA.com following a meeting between WADA President John Fahey and Sepp Blatter, his opposite number at world football's governing body, in Zurich in February, said that cannabinoids accounted for 40 of the 119 adverse analytical cases registered by WADA in football worldwide in 2011.

This was out of more than 28,500 doping samples registered in the sport in total.

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