Australian heavyweight boxing world champion Lucas Browne has on Friday had his World Boxing Association (WBA) title stripped after a "B sample" drug test also returned a positive result for the illicit substance clenbuterol.

Browne, 37, first tested positive for the drug in March, the day he was supposed to fight Russian Ruslan Chagaev in Chechnya, but wasn't stripped of his title until Friday, when the B sample confirmed he had taken the drug clenbuterol.

Browne has maintained innocence throughout the ordeal which has now resulted in a six month ban from fighting, and had questioned why a heavyweight boxer would knowingly ingest a weight-reduction drug.

He had previously said it was possible the drug was present in some food he ate between a prior, clean drug test and the positive test in March.

Clenbuterol is a banned drug on the World Anti-Doping Authority's list and is mainly used for its fat reduction and muscle building benefits.

On Friday, Browne took to social media platform Twitter to confirm the news, but said he would explore his options.

"I'm leaving everything to my lawyer, Mr Leon Margules," Browne tweeted.

"I thank everyone for their support, especially the people and fans of Australia."

The WBA has always maintained that the boxer and his or her team are fully responsible for what enters his or her system, regardless of intent or not.