Tune was summoned to the tribunal after being administered probenecid for a knee infection in March 2001.

But Probenecid can also be used to mask steroid use, and is banned by the International Rugby Board (IRB).

At a three-and-a-half hour tribunal on Monday, a three-member panel was told that neither Tune nor his doctor were aware that the substance was banned.

Tune is now clear to fly to Johannesburg on Tuesday morning for the Wallabies' match Saturday in Johannesburg against South Africa.

"(Tune) acted openly and honestly at all times, including notifying the ARU and the Australian Sports Drug Agency that probenecid had been prescribed because it was necessary medically," the tribunal said in a statement.

"Accordingly, the tribunal declined to apply a sanction."

Lawyer John Gleeson added: "The tribunal was of the view that in this case there were exceptional circumstances."

The Wallaby winger played two Super 12 matches for Queensland and was then withdrawn from four matches when the "doping error" was realised.

Mistakes

The Australian Rugby Union and Queensland rugby officials did not make public Tune's illegal drug-taking or notify the IRB.

Tune said: "I'm very happy. I thought the committee was fantastic. They used their common sense, it went very well."

Saturday's match at Johannesburg is the final match of the round-robin Tri Nations tournament.

Australia need to beat South Africa by 25 points or more and pick up a bonus point if they wants to take this year's title.

Wallaby coach Eddie Jones said Tune's case could have been handled better by rugby authorities.

"The ARU and Queensland rugby have admitted originally there were certainly some mistakes," Jones said on Sunday before leaving with the rest of the team for Johannesburg.