Manchester United boss Sir Alex Ferguson's two-match touchline ban for criticising referee Alan Wiley could lead to further action from the referees' union Prospect. Alan Leighton, national secretary for referees' union, said there was a possibility they could still pursue legal action after Ferguson said the official "just wasn't fit enough" to take charge of United's 2-2 draw with Sunderland last month.

"One of the things we are saying is, is there a case these comments are defamatory?" he said.

"I intend to talk to Alan Wiley to see if he wants to sue on the issue.

"We need to take a few steps back and see what has happened here and I would like to see more about the judgement.

"We never wanted to get lawyers involved in but if referees don't feel they are being protected by the regulatory bodies and someone says something defamatory sooner or later someone is going to take action over it.

"We are going to talk to the relevant authorities to see what it means for the future.

"I'll also talk to our members. I think there will be a concern this isn't an appropriate way to send a message that these comments were wholly unacceptable."

Ferguson, the most decorated manager in the modern game, admitted a charge of improper conduct relating to his comments but Peter Griffiths QC, who chaired the Football Association regulatory commission, said: "It was made clear to Sir Alex that with such stature comes increased responsibilities.

"The commission considered his admitted remarks, in the context in which they were made, were not just improper but were grossly improper and wholly inappropriate.

"He should never have said what he did say."

Leighton believes the authorities missed an opportunity to make a statement to back up the FA's Respect campaign.

"From our point of view it is disappointing. The Football Association had a chance to make a point and they flunked it," he added.

"To question the fitness of referee is to question his ability to do the job and his integrity.

"We don't think this is sending the right message out to other managers.

"This is not a personal vendetta against Sir Alex but he has a particular stature within the game and if he is seen to be getting off lightly other managers may think what he said was not beyond the pale.

"What is interesting is that the commission thought the comments were not just improper but were grossly improper and wholly inappropriate."