Lucas Browne, who vehemently denied knowingly ingesting clenbuterol after he tested positive following a fight in March, has failed another drug test, this time for the stamina-increasing substance ostarine, WBC president Mauricio Sulaiman told RingTV.com on Monday.

Browne enrolled in the WBC’s Clean Boxing Program with VADA in July after he was stripped of a WBA heavyweight title he won by stopping Ruslan Chagaev in the tenth round on March 5. Browne sued the WBA over losing his title, and the WBA, as a concession to Browne to resolve the lawsuit, agreed to allow him to face Shannon Briggs for a vacant WBA ‘regular’ title. Now, the fight with Briggs is in doubt after Browne’s latest difficulty with drug testing. Browne’s “B” sample has not yet been tested, Sulaiman said.

“VADA has reported an adverse finding on Lucas Browne during a random out of competition test under the CBP, which Browne enrolled voluntarily,” Sulaiman wrote in an email on Monday night to RingTV.com. “There will be the process according to protocol. He has the right to open sample B and there will be a full investigation. Each case is different, and it is investigated separately.”

Sulaiman didn’t respond to a question regarding the WBC’s role in drug testing in a fight for a WBA title. When Browne was stripped and suspended for six months in May by the WBA, it was the result of VADA-sponsored drug testing. It’s not clear if the WBC was involved then as it is now. News of Browne’s positive drug test on Monday was first reported by ESPN.com.

WBA president Gilberto Mendoza didn’t immediately respond to an email for comment. Ostarine is the same banned substance which Lucian Bute tested positive for following his draw with Badou Jack on April 30 in a super middleweight title bout.