And the Australian Sports Anti-Doping Authority (ASADA) denies it is sending the wrong message to athletes by placing a tick beside illegal drugs such as methamphetamine, cocaine and heroin on its website that advises which substances are permitted for use out of competition.

As reported in Fairfax Media on Saturday, Mitcham has confessed he battled an addiction to crystal meth in 2011 to try to cope with anxiety and depression.

The report came a day after the AOC board endorsed plans to have Australia's future Olympic athletes and officials sign a legally binding document that they have never taken performance-enhancing drugs.

AOC spokesman Mike Tancred said the committee did not condone the use of illicit or recreational drugs, but they would not be included as part of the planned statutory declaration.

Tancred described crystal meth - more commonly known as ice - as ''a performance ruiner, not enhancer''.

However, the ASADA website, which provides official anti-doping advice to athletes, labels methamphetamine as prohibited in competition.

Under the World Anti-Doping Code, ASADA can only test for stimulants such as methamphetamine during competition.

In the same section of the ASADA website, however, drugs such as methamphetamine, heroin and cocaine have a tick beside them, labelling them as medication ''permitted for use'' out of competition.

Asked if those classifications sent the wrong messages to athletes, ASADA responded: ''The symbols used in the Check Your Substances online resource are simply a guide to the substances' status in sport as per the World Anti-Doping Agency's Prohibited List.

''Drugs such as heroin, cocaine and methamphetamine have serious health consequences. We trust that athletes referring to the Check Your Substances online resource are aware of the health risks associated with these drugs and do not relate a tick as ASADA's endorsement of use.''

The AOC sensationally banned the use of prescribed sleeping medication Stilnox in the lead-up to the London Olympics, responding to media reports of its extensive use among athletes.

Tancred said the AOC had a firm stance against the use of illicit drugs and that athletes were already required to sign a team agreement before representing Australia that ''outlaws the use of recreational drugs'' during competition.

Tancred said the AOC intended to support Mitcham and that the 24-year-old's drug admission would not affect his future selection on Australian teams.

''We've always taken a very tough stance against all drugs and that has not changed,'' he said.

Mitcham did not have a positive test at any point. There was no doubt he was tested during the London Games,'' Tancred said.

''Whilst we frown upon the use of recreational drugs and we're disappointed on one hand that he's admitted he's taken this drug, we'd also like to support him because it's a hideous thing, he's having treatment and we'd like to see him overcome it and continue on in his sport and his career.

''We also frown on the use of recreational drugs because people like Matthew Mitcham are role models to thousands of young kids and I'm sure he'd be disappointed from that aspect.'' Already, the AOC has decided not to make minors sign the statutory declaration to represent Australia at events such as the Youth Olympics.

Asked if Olympic athletes under 18 would need to sign the statutory declaration, Tancred said: ''That will have to be determined by the AOC at a later date.''

The impending statutory declaration will not prevent the selection of athletes who have served a doping ban. That clears the way for athletes such as Canberra boxer Bianca Elmir, who was dumped from the London Olympic team for testing positive to a banned diuretic, to resume an Olympic career once she completes her 12-month suspension.