Tyson Fury appeared to announce his retirement on Monday in a foul-mouthed tweet.

The controversial heavyweight champion has twice pulled out of defending his WBA and WBO belts against Wladimir Klitschko, whom he defeated in November last year to claim the titles. An ankle injury and undetermined health concerns led to the two rematches being postponed.

Widespread reports last week claimed Fury had tested positive for cocaine, although no official statement has been forthcoming from the authorities or the man himself. The Voluntary Anti-Doping Association (VADA) declined to comment on the results of any test when contacted by Omnisport last Friday. 

On Saturday, Fury posted a photo of his head super-imposed onto an image of Tony Montana, the protagonist from 1983 film Scarface played by Al Pacino.

The photograph shows fictional drug lord Montana reclining in his chair with bags of cocaine littered over a table in front of him.

And Fury took to Twitter again to seemingly announce his retirement from the sport.

"Boxing is the saddest thing I ever took part in, all a pile of s***, I'm the greatest, & I'm also retired, so go suck a d***, happy days," he wrote.

On Sunday, Fury's uncle and trainer Peter Fury also took to Twitter, claiming "you don't win world titles on coke", and challenging anyone "that's not happy go tell Tyson to his face".