Australia suffered its worst swimming haul in decades in London, winning just one gold medal, six silver and three bronze for its lowest tally in the pool since Barcelona in 1992.

It was the first time since Montreal in 1976 that an Australian had failed to win an individual gold medal. 

The Australian newspaper claimed that breakdown in discipline had occurred, with insiders claiming that transgressions by the world champion men's 4x100 metres freestyle relay team were overlooked because of their so-called special status.

It said there were "persistent reports" that some members of the six-man relay team had an initiation ritual in the days leading up to the Games which involved taking Stilnox, a sleeping medication banned by the Australian team.

The "bonding" night also including the swimmers upsetting some teammates and coaches by prank calling and knocking on their doors late at night at their camp in Manchester, two days before the team went to London.

Several of the six relay swimmers, who failed to win a medal in that event despite being heavily favoured, confirmed they had misbehaved on the night, although none would admit to taking Stilnox.

The team finished fourth in London in a race won by France.

"The prank calls did happen but we weren't under the influence of anything," Matt Targett told the paper.

James Magnussen's manager Mark Jones agreed the relay team "acted up a bit".

"They knocked on some people's doors and made prank calls but at absolutely no time was there any use of Stilnox or alcohol or any other substance," he said.

Australia's head coach Leigh Nugent claims that following London 2012 everyone "needs to pull together"

Head coach Leigh Nugent refused to comment on the allegations but his post-London 2012 report was leaked to the Sydney Morning Herald. 

It did not mention any disciplinary problems or lack of cohesion.

"It appears evident following the barrage of criticism the expectation placed on this team was based on the fantasy that the result from four years prior will automatically repeat itself regardless of the comparative world positioning," he wrote, according to the leaked document.

"Our process is to evaluate objectively and to continue to improve from the low base we started from in 2009 and establish a higher platform to launch from in 2013.

"This is a time where we all need to pull together, not fall apart."

The exact terms of reference and structure of the investigation are still being framed. 

Libby Trickett, who helped Australia to the women's 4x100m freestyle relay gold in her third Olympics, said the team spirit had not been the same as she had previously experienced.

"Obviously this is the first year I've been on the team since 2009, and I just felt in previous years there was a more cohesive unit," she told Fox TV.

Contact the writer of this story at [email protected]