OTTAWA, Canada (AFP) - Rob Ford is being sued by his sister's former common-law husband who is alleging the Toronto mayor arranged to have him beaten to keep him quiet about Mr Ford's drug use, it was reported on Wednesday.

Mr Scott MacIntyre made the allegations in a statement of claim, cited by the daily Toronto Star, in which he says Mr Ford was "indirectly" involved in the March 2012 jailhouse assault.

Mr MacIntyre's leg was reportedly broken and his teeth knocked out in the melee.

He alleges that Mr Ford mistook comments in a letter he'd written to his sister Kathy as a threat "to disclose Ford's drug and alcohol abuse and association with criminals". The suit alleges he responded by sending Mr MacIntyre "a firm message to prevent him from doing so".

The mayor's lawyer, Dennis Morris, confirmed the allegations to reporters but declined to comment further, except to say Mr MacIntyre was in prison at the time for having threatened the mayor.

Mr Ford has been mired in scandal for months, accused of unseemly behaviour and sexual harassment during a series of drunken rampages - in addition to his admitted crack use.