SYDNEY (AP) -- Former world swimming champions James Magnussen and Eamon Sullivan, and their 4x100-meter relay teammates, could face sanctions after admitting to taking the sleep medication Stilnox during a "bonding session" ahead of last year's London Games.
Magnussen, Sullivan, Tommaso D'Orsogna, Cameron McEvoy, James Roberts and Matthew Targett held a press conference Friday with Swimming Australia president Barclay Nettlefold. They released a joint statement admitting they took Stilnox and engaged in disruptive behavior including making prank calls during the Australian team's pre-games camp in Manchester.
Roberts later said he did not take Stilnox, while Sullivan said the remaining members of the relay team took one tablet each.
"In hindsight it was a ridiculous choice and ridiculous method ... but I don't feel it affected my performance," Magnussen said.
The medication is not a banned substance, but the Australian Olympic Committee prohibited its athletes from using it ahead of the London Olympics after former swimmer Grant Hackett revealed he became dependent on sleeping pills during his career.
Sullivan said the Stilnox was obtained with a doctor's prescription in Australia before the AOC ban.
AOC secretary general Craig Phillips said possible sanctions against the swimmers could include a withdrawal of their funding in the lead up to the 2016 Rio Olympics. The AOC could also ask for money paid under its medal incentive scheme to be returned, meaning Magnussen could be forced to pay back $10,000 given to him for winning a silver medal in London.
The swimmers admitted some of them played pranks on other team members such as knocking on doors and making phone calls, but denied entering any rooms. They said they were asleep by 10.30 p.m. that night.
Australian head swimming coach Leigh Nugent was told of the pranks the following morning, but reportedly took no action.
Phillips said the body would await the outcome of Swimming Australia's newly-formed integrity panel, which will also investigate the swimmers, before deciding on the severity of its punishment.
The swimmers' admissions came after an independent review into the team's disappointing performance in London. The review described a "toxic" environment, including misuse of prescription drugs and bullying.
"As a result of the revelations this week arising from the swimming reviews, the AOC has decided to engage a Queens Counsel (senior lawyer) to investigate these incidents further," Phillips said in a statement.
Australia's only swimming gold at the Games was in the women's 4x100-meter freestyle relay, with the high-profile men's relay and Magnussen failing to deliver on expectations in a country accustomed to strong performances in the Olympic pool.
In what was Australia's worst Olympic swimming performance in two decades, the team won only 10 medals overall, including six silver and three bronze.