Chelsea's Mikel Obi (R) talking with referee Mark Clattenburg during the match
The Football Association has begun an investigation into allegations made by Chelsea against referee Mark Clattenburg following Manchester United's 3-2 win at Stamford Bridge.
Chelsea have made a formal complaint against Clattenburg, accusing him of using "inappropriate language" towards two of their players on Sunday.
It is claimed Clattenburg used racial language, BBC Sport has learned.
Clattenburg has not been picked to officiate at a match this weekend.
A statement from referees' body the Professional Game Match Officials board said: "PGMO believe that with any football match the focus should not be on the officials but on the players and the game itself.
"Mark Clattenburg is one of the elite referees in world football and, in these circumstances, the intense level of scrutiny would detract from the match and be unfair to the clubs and the supporters of both sides."
The FA issued a statement on Monday confirming it has launched an investigation, adding it will make "no further comment at this time".
It is understood midfielder John Mikel Obi is involved in the complaint.
When Chelsea confirmed they would be making a complaint on Sunday, PGMO issued a statement confirming Clattenburg would co-operate with any investigation.
"PGMO is aware of the allegations and they are being treated with the utmost seriousness," the statement read.
"Mark will co-operate fully and welcomes the opportunity for the facts to be established."
Clattenburg, 37, is viewed by the PGMO as one of the country's leading officials and is on the FIFA list.
The Durham-born referee was put in charge of the League Cup final in February and the Olympic final between Brazil and Mexico in August.
Former Premier League official Graham Poll has suggested Chelsea's complaint could hinge on evidence from Clattenburg's assistants and the fourth official.
Linesmen Michael McDonough and Simon Long and fourth official Michael Jones may have heard conversations between Clattenburg and the players because all four officials wear microphones and ear pieces that allow them to hear what each other is saying during the game.
"A referee's microphone is on open. Everything he says is heard by [his or her] assistants," Poll told BBC Radio 5 live.
"So if Mark said something, the assistants would have heard it."
Metropolitan Police commissioner Bernard Hogan Howe said the police have not received any complaint about the alleged comments.
"If we hear of any report, we will look into it," he confirmed.
But the Metropolitan Police have revealed that an investigation has been launched into an incident in which a steward was injured at Stamford Bridge.
It occurred as Javier Hernandez celebrated United's winning goal in the 75th minute.
During the controversial encounter, Clattenburg sent off two Chelsea players.
Branislav Ivanovic and Fernando Torres were shown red cards in the space of five minutes, with the latter's second yellow card for diving disputed by the Blues.