As the Australian swimming community spoke out in defence of Sullivan, who set a new world mark of 21.56sec in Sydney in February, a source close to the swimmer said he would seek legal advice about whether he could pursue Hall for damage to his reputation. It is understood Sullivan's management was waiting to see a full version of Hall's comments before consulting with defamation lawyers.

Sullivan said in a statement, "Obviously I'm disappointed with [Hall's] comments as I have a lot of respect for what he has achieved in the pool. I look forward to hopefully racing him in Beijing, but at the moment my focus is on getting into the Australian team."

Hall, infamous in Australia for promising before the 2000 Olympics to smash the Australian 4x100m relay team "like guitars", said Sullivan's big improvement would raise eyebrows in the international swimming community. The American said he was not accusing Sullivan of cheating but compared the Western Australian's improvement to that of a drug cheat.

Hall, who hopes to win a third straight Olympic 50m freestyle title in Beijing, said he had never seen such a drop in time from an elite level swimmer as Sullivan's move from 22.00 to 21.56 in breaking Russian great Alex Popov's world mark by 0.08.

Australian swim team captain Grant Hackett described Hall's comments as "ridiculous".

"These comments are absolutely ridiculous and are stated with no substance," Hackett said in a Swimming Australia statement.

"Australian swimming has no evidence of drug culture, no history of it and these comments are totally irresponsible."

Australian head coach Alan Thompson agreed.

"These comments are laughable from a guy who has no credibility," Thompson said.

"Gary Hall Jr is a fantastic swimmer who has achieved a lot in the pool but every time he opens his mouth he says something ridiculous and this is just an extension of that."

with AAP