Lucas Browne's promoters are investigating the Australian heavyweight boxer's second positive doping result in a year, saying it is "a bitter blow" after his previous exemption.

Hatton Promotions issued a statement early Wednesday saying it was aware of reports Browne had failed a test undertaken recently as part of the World Boxing Council's clean boxing program.

This comes seven months after he tested positive for the banned substance Clenbuterol following the March 5 bout against Ruslan Chagaev of Uzbekistan, which he won in a 10th-round technical knockout.

Browne was suspended by the World Boxing Association following that test but was later cleared after alleging his food was deliberately contaminated, and was scheduled to fight Shannon Briggs for the WBA's "regular" title by the end of the year.

"Clearly the test results are hugely disappointing for the company and for Lucas himself," the statement said.

"For a man and a team who fought so hard to clear his name following what is now universally accepted to have been a deliberate contamination of products he ingested prior to his March fight with Ruslan Chagaev, this is a bitter blow.

"Lucas was cleared of any deliberate wrongdoing a few months ago and we feel it would be somewhat unfair and incorrect for anyone to suggest that the results of his latest test bring the outcome of his previous exoneration into question."

Hatton Promotions said it wouldn't comment further until it had conducted a full investigation, including prescribed medication and supplements, of the latest case.