Local law enforcement has launched an investigation into the ref's actions.

The Metropolitan Police has launched an investigation into alleged comments by referee Mark Clattenburg towards Chelsea players during the club's 3-2 defeat against Manchester United on Sunday.

"An investigation has been launched into alleged comments made during a football match between Chelsea FC and Manchester United FC at Stamford Bridge on 28 October 2012," read a police statement.

"This follows on from a complaint received by the Metropolitan Police Service on 29 October. Officers from Hammersmith & Fulham borough are in liaison with Chelsea Football Club and the Football Association.

"At this time, the MPS has not received any complaint from either Chelsea Football Club, or the Football Association. We continue to work in partnership with Chelsea Football Club and the Football Association in order to consider any allegation that is made in relation to the reported events."

Clattenburg endured a tough afternoon at Stamford Bridge on Sunday as he controversially sent off Fernando Torres before allowing an offside Javier Hernandez goal to stand.

His refereeing performance was the least of his worries, however, as Chelsea filed a complaint to the Premier League two hours after the final whistle regarding inappropriate and racist language used by Clattenburg towards two Blues players.

The Football Association has made its own investigation into the issue but neither the club nor the FA, were responsible for telling the police.

The Metropolitan Police Service confirmed it had acted on what was described as a "complaint" made by Peter Herbert, a lawyer representing the Society of Black Lawyers.