LONDON: The Football Association on Monday launched an investigation into claims referee Mark Clattenburg used “inappropriate language” towards two Chelsea players during their match with Manchester United on Sunday.

British newspaper reports claimed the language allegedly used by Clattenburg included a racial insult directed towards Chelsea's Nigerian midfielder John Mikel Obi.

The other player involved is reported to be Spanish midfielder Juan Mata.

Chelsea made an official complaint to the Premier League match delegate, whose report was due to be transferred to the FA on Monday.

“The FA has begun an investigation relating to allegations made following Sunday's fixture at Stamford Bridge between Chelsea and Manchester United,” read a statement from the FA.

“The FA will make no further comment at this time.”

Clattenburg aggrieved Chelsea by sending off two of their players and allowing an offside United goal to stand in the European champions' 3-2 defeat at Stamford Bridge.

The 37-year-old referee pledged to co-operate fully with the football authorities after the allegations became public on Sunday evening.

Clattenburg is likely to be interviewed by FA compliance officers, who are expected to speak to Mikel and Mata as well as other potential witnesses.

The evidence supplied by Clattenburg's fellow match officials is likely to be a central component of the investigation, as the four-man team would have been communicating via microphones and earpieces throughout the game.

Mikel's agent, Chelsea, and United all refused to comment on the incident on Monday, while Mata made no reference to it in an article on his personal blog.

The Professional Game Match Officials body, which manages officials in the Premier League, confirmed later on Monday that Clattenburg will not officiate a match this weekend.

“With any football match, the focus should not be on the officials but on the players and the game itself,” said the organisation.

Meanwhile, the Metropolitan Police have announced an investigation into an incident in which a steward was injured towards the end of Sunday's game. Chelsea have already launched their own inquiry, after reports that the steward fell as home fans threw objects onto the pitch in the aftermath of Javier Hernandez's winning goal for United.

The steward reportedly injured his knee in the incident and needed approximately 10 minutes' treatment by paramedics before being taken to hospital.

A police spokeswoman said: “We are aware of an incident during yesterday's match at Stamford Bridge in which a steward was injured.

“An investigation has been launched into the incident and our inquiries continue.”