London - London's Metropolitan Police said on Tuesday they were investigating alleged racist comments made by the referee during last weekend's English Premier League match between Chelsea and Manchester United.
Scotland Yard said they were looking into the allegations against Mark Clattenburg, who refereed Sunday's clash at Stamford Bridge in west London. Visitors United won 3-2, with Chelsea having two players sent off.
"An investigation has been launched into alleged comments made during a football match between Chelsea FC and Manchester United FC at Stamford Bridge," a police statement read.
Officers from the local borough were in touch with Chelsea and the Football Association, the sport's governing body in England, it said, adding that neither party had made a complaint.
Scotland Yard said they were working with the Blues and the FA "in order to consider any allegation that is made in relation to the reported events".
Clattenburg is alleged to have used "inappropriate language", reportedly of a racist nature, towards Chelsea's Nigeria and Spain midfielders John Mikel Obi and Juan Mata at the west London club's Stamford Bridge ground on Sunday.
The 37-year-old official, who has vowed to co-operate fully with any probe and reportedly denies the allegations, has been stood down from matches for a week, pending an FA investigation.
The racism claims are the latest to hit the English Premier League, notably after Chelsea captain John Terry, the former England skipper, was cleared earlier this year in a criminal trial of racially abusing QPR's Anton Ferdinand.
Terry was later found guilty at an FA disciplinary hearing, which has a lower burden of proof, and banned for four matches.
Racism is still a source of friction among some black players, who say that the game remains affected by it, despite efforts to stamp it out.
Peter Herbert, head of the Society of Black Lawyers, said on Monday the organisation had written to the police to request an investigation into Clattenburg's alleged comments.
"Our information is that racist remarks were directed at John Mikel Obi and at Juan Mata. If so, that is wholly unacceptable in any circumstances," the letter stated.