Former Premier League referee Mark Halsey has revealed that he was in regular contact with Sir Alex Ferguson during the Scotsman's time as manager of Manchester United.

The 52-year-old made the claims in his book Added Time, stating that he once asked Ferguson to defend fellow referee Mark Clattenberg following allegations that he verbally abused Chelsea's John Obi Mikel.

Ferguson later backed Clattenburg during a press conference before the Football Association decided against taking any action against the match official.

"It took time to gain Sir Alex Ferguson's respect but in the end we had a very good relationship," the Daily Star quotes Halsey as writing in his book.

"One thing should be made clear about my relationship with Sir Alex. I may have spoken to him a lot and shared texts but he knew when I crossed that white line there were no favours. Players and managers would not respect you if you gave decisions based on friendship."

Ferguson and Halsey both retired at the end of last season.