(CNN) -- The racism row involving a Premier League referee could dominate English football headlines for some months, after police announced on Tuesday that they had launched an investigation into the incident.
Mark Clattenburg, who took charge of Chelsea's controversial 3-2 home defeat by Manchester United on Sunday, is alleged to have made "inappropriate" comments to two Chelsea players, one of which is claimed to have had a racial nature.
The footballers in question are midfielders John Obi Mikel of Nigeria and Juan Mata of Spain.
If the police inquiry escalates to a formal charge for Clattenburg, there is unlikely to be any ruling until well into next year.
It took nine months for John Terry to be cleared by a criminal court in London after the Chelsea captain was accused of racially abusing Queens Park Rangers defender Anton Ferdinand in October 2011.
The English Football Association, which launched its own investigation into the Clattenburg affair on Monday, subsequently found Terry guilty of racial abuse, banning the 31-year-old for four matches as a result.
"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 the London police force statement.
"This follows on from a complaint received by the Metropolitan Police Service on 29 October.
"Officers ... are in liaison with Chelsea and the Football Association. At this time, the MPS has not received any complaint from either Chelsea or the Football Association."
Peter Herbert, a leading human rights barrister who chairs the Society of Black Lawyers and who has recently staged talks over a black footballers' association in light of recent racism scandals in the English game, says he made the complaint to the police.
"What we don't want is for it to be swept away under the carpet," he told British broadcaster Sky Sports. "It must be subject to a full and proper investigation. It is to lend some seriousness and some weight behind what is happening in football."
The FA's decision to run its own inquiry at the same time as the police investigation has been welcomed by Gordon Taylor, the chief executive of the Professional Footballers' Association, who is keen for the incident to be resolved far quicker than the Terry affair.
Meanwhile, Clattenburg, who refereed the Olympic Games football final in August and who has welcomed the FA inquiry, has been stood down from the elite panel of referees set to officiate Premier League games this weekend.
The 37-year-old has already filed what is known as an "extraordinary incident report," which is believed to deal with an alleged confrontation that took place in the referees' room after the final whistle.
The UK Press Association reported that Mikel accused Clattenburg of abusing him during the post-match conversation, which was observed by Chelsea manager Roberto Di Matteo, assistant manager Eddie Newton and chief executive Ron Gourlay.
On Tuesday, newspaper reports suggested that neither Mikel nor Mata heard any abusive comments but were informed of them later by their teammates.
Clattenburg and his three assistants were all wearing microphones and earphones, but FIFA rules do not permit the recording of such conversations as there is no provision for this in the laws of the game.