Australia has banned its athletes at the London Games from taking strong sedatives after former Olympic champion swimmer Grant Hackett said he had become reliant on Stilnox, a brand of the medication zolpidem.

The 400 or so athletes heading to London could have their rooms searched and face punishment up to and including expulsion if found to be in breach of the ban, Australian Olympic Committee chief John Coates said.

"We have decided to amend our team medical manual to make it absolutely unequivocal that we prohibit the use of Stilnox and other related drugs," he said. "If, in extreme circumstances, they still need to be prescribed drugs, there is a short-acting drug temazepam, which does not have the same addictive and hallucinatory effects as zolpidem."

Hackett won the 1,500 metres freestyle gold at the Sydney and Athens Olympics but came up just short of a third successive title in Beijing four years ago.

In an interview with the Sunday Herald Sun newspaper last weekend, the 32-year-old said he had been prescribed Stilnox, which is not banned by the World Anti-Doping Agency, to battle insomnia and described it as "evil".

"I have to acknowledge that this was only brought to my attention when I read Grant Hackett's revelations," Coates said.

"If I'm to blame for not having got on top of it earlier, I accept that blame."

Coates said Hackett had told him he had been introduced to the drug at the 2003 world swimming championships and the use of Stilnox had been "widespread" among swimmers by the time of the Beijing Olympics.

Hackett's reputation has taken a battering in recent months with stories about a messy separation from his wife and pictures showing his wrecked apartment.