Rusedski has struggled with injury

The British number two confirmed that he had failed a drugs test, but pleaded his innocence.

"In response to media inquiries, I can confirm that a sample has tested positive for a low level of nandrolone," he said in a statement.

The 30-year-old, who could face a two-year ban if found guilty, will face a hearing in Montreal on 9 February.

Rusedski added: "I shall attend and I fully expect to be found innocent. I do not and have not taken performance-enhancing drugs."

The test dates from a tournament he played in the summer in Indianapolis during an injury-plagued season when he competed in only six tournaments.

Rusedski loses in Adelaide

He has only just returned to tennis after an absence with back, knee and foot injuries.

The Canadian-born player lost the second match of his comeback in Adelaide on Thursday.

Officials from the Association of Tennis Professionals said Rusedski, who is entered for the Australian Open starting in Melbourne on 19 January, was still in Adelaide and was expected to fly to Sydney for next week's Adidas International.

Australian Open chief Paul McNamee said the player was still welcome at Melbourne Park.

"The Australian Open prides itself on welcoming any eligible player to Melbourne Park, and Greg certainly deserves that," he said.

He [Rusedski] is certainly welcome in Melbourne Australian Open chief Paul McNamee

"He hasn't been found guilty or sanctioned.

"We know there's been an initial infringement but until the hearing - where he will be either found guilty or, as Greg believes, will be found innocent - there's no sanction on him at all.

"Those are the rules of tennis and under those rules he is able to play.

"If Greg hadn't spoken about this we wouldn't even know about it now. He is certainly welcome in Melbourne."

An ATP spokesman said Rusedski would be allowed to compete on the tour until his February hearing.

The highpoint of his career was a run to the final of the US Open in 1997 when he lost to Australia's Pat Rafter.