Manchester United manager Alex Ferguson has been told by the Football Association (FA) to explain his reported comments suggesting the ruling body had done "a deal" with Arsenal over a recent disciplinary hearing.
A statement on the FA official website on Wednesday said his comments "appear to raise issues about the integrity and impartiality of the FA's disciplinary process".
The FA has also written to United asking if his comments reflected their position as a club.
Ferguson and United have been given until November 11 to respond.
Ferguson was unhappy about punishments given to title rivals Arsenal and their players following incidents during and after a premier league match between the teams in September.
The FA fined Arsenal and several of their players a total of 275,000 pounds this month for their involvement in the fracas.
Four Arsenal players -- Patrick Vieira, Martin Keown, Ray Parlour and Lauren -- received suspensions totalling nine games but the league leaders suffered no loss of points.
Ferguson said Arsenal had struck a deal to minimise their punishment.
"I read in the papers this morning that they (Arsenal) did a deal (with the FA) before they went in there and I think that was the suspicion right through the country, that there was a deal been done," he said.
United players Ryan Giggs and Cristiano Ronaldo were also charged by the FA for their part in the disorder, which followed a last-gasp penalty miss by United striker Ruud van Nistelrooy in the 0-0 draw on September 21.
The cases of the United players have still to be heard.
Arsenal manager Arsene Wenger said the punishment had been severe but added that even if the players were hanged in London's Hyde Park it would not be enough for some of the club's critics.
United defender Rio Ferdinand was charged with misconduct by the FA last month for missing a drugs test.
Ferguson was handed a two-match ban and 10,000 pounds fine last month for abusing a match official during a premier league game at Newcastle United on August 23.
