Alan Wiley has ended speculation that he could sue Manchester United boss Sir Alex Ferguson for defamation, after comments made regarding the referees fitness after a 2-2 draw with Sunderland last month. Ferguson has already received a £20,000 fine for his suggestions that Wiley was not fit enough to referee the tie effectively, and has also apologised.

Wiley said: "Although I was bitterly disappointed about the personal attack on me, I want to put this behind me and continue to concentrate on my refereeing."

The referees union Prospect has also written to the FA to seek greater support for referees and calling for stronger action if there are similar attacks in the future.

Prospect national secretary Alan Leighton said: "Unwarranted and untrue attacks on referees damage the hard-earned reputation of our members, call into question their integrity and damage the image of the game by suggesting that the referees are incapable of doing their job.

"Referees understand and accept that their decisions will be questioned, but personal attacks are unacceptable."

Leighton also defended Prospect against criticism that it had chose this case to become very publicly involved.

He added: "Prospect adopted a policy when we started representing referees four years ago that we would not make public comment on every criticism made by ex-referees or managers.

"The seriousness of the recent attack forced the union to depart from that policy. We will, however, continue to defend members where their professionalism is publicly questioned."