Darron Gibson's proposed departure from Manchester United has been placed in doubt after he damaged ankle ligaments in training, an injury that could sideline him for at least four weeks.

Gibson, linked with Aston Villa and Blackburn Rovers, was taken to hospital on Thursday and a protective cast has been placed on his right foot while he waits for the swelling to go down so an x-ray can ascertain the seriousness of the injury.

The 23-year-old midfielder has been told he no longer forms part of Sir Alex Ferguson's plans and is looking for a new club after talks with Sunderland collapsed earlier in the summer. The Republic of Ireland international was not taken on United's pre-season tour of the United States and has been omitted from Ferguson's first-team squad so far this season.

United will continue trying to take him off their wage bill before the transfer window closes next week but Gibson's injury has raised concerns within the club that potential buyers may be put off.