London - Tyson Fury was fighting for his boxing future on Friday after a media report said he had tested positive for cocaine and faced being stripped of his heavyweight title belts.
The 28-year-old Briton had been due to defend the WBA and WBO world titles against former champion Wladimir Klitschko in Manchester on October 29, but the bout was called off abruptly last week for a second time, for unspecified medical reasons.
A spokesman for Fury's promoters Hennessy Sports declined to discuss the cocaine claims, which were made by US-based broadcaster ESPN, which said that the troubled Fury tested positive after giving a random urine sample on September 22.
Contacted by Press Association Sport, the spokesman said the beleaguered Fury camp would not be making a statement.
ESPN reported Fury was tested by the Voluntary Anti-Doping Association (VADA), which is based in Las Vegas, as part of the routine agreed by both fighters before the fight.
One attempt at a rematch with the Ukrainian Klitschko, scheduled to take place on July 9, had already been abandoned because of an apparent ankle injury sustained by the controversial British fighter.
Contacted for comment regarding Fury, VADA, which specialises in testing competitors from boxing and mixed martial arts, said it does not release results of samples unless at an athlete's request.
Providing the test was taken on an out-of-competition basis, Fury stands to face no sanctions such as a ban.
But he risks losing his belts due to inactivity, ESPN said, having failed to make a title defence this year.
If confirmed, the cocaine claim would be the latest in a series of damning episodes for the British boxer.
After his ankle injury it then emerged that UK-Anti Doping (UKAD) had charged the champion over a urine sample taken in February 2015, and his cousin Hughie with a doping offence.
It was alleged the sample - taken nine months before Tyson Fury's defeat of Klitschko to take his belts - contained traces of the banned substance nandrolone.
Fury was provisionally suspended, but that ban has since been lifted and his legal team had said they would be suing UKAD over the allegations. His hearing will be held in November.