James Magnussen and his team-mates from the Australian men’s 4x100m freestyle relay squad have admitted using a sedative banned by their national Olympic committee in a bonding session before the London Games.

The prescription drug Stilnox was banned by the Australian Olympic Committee (AOC) just before the 2012 Games and the athletes now face sanctions from the governing body for breaching their Olympic team membership agreement.

Stilnox is not banned by the World Anti-Doping Agency but was prohibited by the AOC because of its hallucinatory effects and after former Olympic champion Grant Hackett said he had become addicted to it.

“We stand here collectively to confirm that we did take part in a bonding exercise during which members of the relay team took Stilnox,” the six swimmers said in a statement read out at a news conference in Sydney yesterday.

“We acknowledge by our recent action in continuing a recent tradition in the Australia swim team, we have let ourselves down and the people who have supported us.”

Olympic silver medallist Magnussen and his team-mates Matt Targett, Eamon Sullivan, James Roberts, Cameron McEvoy and Tommaso D’Orsogna apologised for their actions.

The statement said the drug had been prescribed before the AOC ban and the swimmers had then indulged in “childish” and “stupid” pranks such as knocking on the doors of other athletes.

The AOC said they would be appointing a lawyer to conduct an investigation into these and other disciplinary issues relating to the swimming team in London.

Magnussen received A$10,000 ($10,300) from the AOC for winning a silver medal in the men’s 100 metres freestyle, while Targett and D’Orsogna were paid A$7,500 for bagging a bronze as part of the 4x100m medley relay team.

The athletes face the possibility of losing part or all of those rewards as well as funding for preparation for major events, including the 2016 Olympic Games.

Magnussen was hot favourite to win the 100 freestyle in London and suggested the weight of expectation on him contributed to him agreeing to take the drug.

“I think one of the reasons that I agreed to go along with this was I was feeling under so much pressure and it had been building for the best part of a year,” the 21-year-old said.

“I have a lot of regrets, but I don’t feel it affected my performance.”

Misuse of prescription drugs along with allegations of drunkenness, breaching curfews, deceit and bullying were highlighted in a review published earlier this week, which said slack management had allowed a “toxic” culture to develop in the team.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.