Tyson Fury and Wladimir Klitschko's world heavyweight title rematch has been postponed for a second time after the Briton was declared "medically unfit" to fight in Manchester next month.

Fury's reign as WBA and WBO champion is likely to now extend to a year without him defending it, having toppled the Ukrainian great in Germany last November.

An original rematch scheduled for June was called off after the Manchester fighter suffered a sprained ankle, although the reasoning for the latest postponement is less clear.

Fury's management company gave little away in confirming the fight, scheduled for October 29, was off.

A statement read: "Tyson has, this week, been declared medically unfit to fight. 

"Medical specialists have advised that the condition is too severe to allow him to participate in the rematch and that he will require treatment before going back into the ring. Tyson will now immediately undergo the treatment he needs to make a full recovery.

"We and Tyson wish to express our sincerest apologies to all those concerned with the event and all the boxing fans who had been looking forward to the rematch. Tyson is understandably devastated by the development."

UK Anti-Doping (UKAD) provisionally suspended Fury in June over a failed drugs test, taken nine months before he beat Klitschko. Fury is adamant that he is a clean athlete and has threatened UKAD with legal action.

Klitschko himself has suggested that he will take Fury to court over negotiations for the rematch, and his camp is likely to be distinctly unimpressed by another rearrangement.