Embattled Toronto Mayor Rob Ford has apologised for a video of him making threats to commit "first-degree murder" against an unknown person.

The leader of Canada's biggest city told reporters he had been "extremely inebriated" in the clip, which shows him apparently blowing off steam.

It is the latest controversy to engulf the mayor, who admitted this week having smoked crack cocaine.

The BBC Rajini Vaidyanathan in Toronto said that the mayor was continuing to work from his office at City Hall despite the emergence of the video.