SYDNEY (Reuters) - Multiple Olympic champion Ian Thorpe is back training and that could become the catalyst for a return to competitive swimming, his long-time agent has said.

The 'Thorpedo' retired from the pool in 2006 and the Australian has knocked down several media reports since then which said he was considering a comeback.

However, his agent David Flaskas told Sydney's Sun Herald newspaper the 28-year-old was now back in training.

"I still think he's got competitive juices but he also understands what it takes to compete at the level he competes at.

"There's a lot of water to pass under the bridge but the one thing he is doing is enjoying it and, as he has said before, 'You never say never'."

A weight training accident and then a car crash at the Beijing Olympics, where he was a commentator, required him to return to the pool to rehabilitate a shoulder injury.

Flaskas said the pair had not spoken about next year's London Olympics and Thorpe had not notified Swimming Australia that he wanted to compete again.

He must be on the drug-testing register for nine months before he can compete again, the newspaper said.

"In Beijing at different times there were times he missed the racing and I have no doubt he thinks about London," Flaskas was quoted as saying.

"He's loving swimming all over again, but he's not asked me to apply to Australian swimming to get into the drug-testing regime.

(Reporting by Greg Stutchbury in Hamilton; Editing by Ken Ferris)