Referee Mark Clattenburg accused of aiming racist insult at Chelsea & Nigerian midfielder John Obi Mikel

Referee Mark Clattenburg has been accused of aiming a racist insult at Chelsea midfielder John Obi Mikel during Sunday's 3-2 home defeat by Manchester United at Stamford Bridge.

Chelsea made a complaint to the Premier League after Mikel stormed into the referee’s room to demand an apology after claiming Clattenburg made a racist slur when he booked the midfielder in the 76th minute.

One of Chelsea’s Spanish stars is also involved after players claim they heard Clattenburg refer to him as ‘a Spanish t**t’. Spaniards Fernando Torres, Juan Mata and Cesar Azpilicueta all played against United.

Chelsea made the official complaint at 7.45pm on Sunday night, but Clattenburg had already been confronted by then.

Chief executive Ron Gourlay, with Mikel and manager Roberto Di Matteo, demanded an apology during stormy scenes in the referee’s room.

Clattenburg refused and Chelsea decided to take the incredible action of launching an immediate complaint to the Premier League over his language.

Home players heard the alleged comment to Mikel and will back up his story. Clattenburg said he would co-operate with any inquiry.

Professional Game Match Officials, the body which represents Premier League referees, released a statement which read: ‘PGMO is aware of the allegations and they are being treated with the utmost seriousness. Mark will co-operate fully and welcomes the opportunity for the facts to be established.’