The FA is to look into Sir Alex Ferguson's comments that Arsenal may have done a deal with English football's governing body over the Old Trafford melee.
Earlier this week Arsenal and five of their players were given collective fines of £275,000 and bans totalling nine matches by the FA following the fracas between Arsenal and United players in September.
On Friday Ferguson said: "I read this morning they did a deal before they went in there and I think that was the suspicion right throughout the country, that a deal was being done.
"It's disappointing to read that kind of thing."
FA spokesman Adrian Bevington said: "Further to comments made by Alex Ferguson in this morning's newspapers the FA would like to make clear that it is looking very closely at the alleged allegations."
Ferguson's comments drew a barbed response from Arsenal manager Arsene Wenger.
He said: "Only the FA can respond. I cannot answer every opinion in the whole country.
"Even if you hang us, it is not enough for some people.
"They want to hang us twice, and maybe at Hyde Park in front of the whole country."
The FA have also hit back at further claims made by Ferguson over the treatment of Rio Ferdinand following his missed drugs test.
The central defender has been charged with misconduct after failing to attend a drugs test at the club's training ground despite having been requested to do so.
Strong denial
Ferguson claims the FA are responsible for leaking the player's name to the media, but the FA insists that is not the case.
Bevington said: "We strongly refute any suggestion that we have 'hung the player out to dry'.
"We have conducted the whole disciplinary process in the standard procedural manner and at no time did the FA in any way leak the player's name to the media.
"We will defend our position strongly against any accusation of this kind.
"The first time Rio Ferdinand was named by the FA was the day of the squad announcement for the (England) game in Turkey, by which time Rio's name was unfortunately known to the media from other sources."