Britain's world heavyweight champion Tyson Fury said he was now "here to stay" just hours after announcing his retirement from boxing yesterday.

"Boxing is the saddest thing I ever took part in, I'm the greatest, and also retired," Fury said in an expletive-filled rant on Twitter.

A few hours later, however, the 28-year-old revealed he was planning to carry on fighting.

"Hahahaha u think you will get rid of the GYPSYKING that easy!!! I'm here to stay. #TheGreatest just shows u what the Medea are like. Tut tut," he said.

Fury has tested positive for cocaine, ESPN reported last week citing a leaked letter sent by the Voluntary Anti-Doping Agency (VADA). Reuters was unable to verify details of the report.