Mark Clattenburg and the FA are both waiting to discover whether police will investigate allegations the referee used "inappropriate language" towards Chelsea stars John Obi Mikel and Juan Mata.

Clattenburg became the latest high-profile football figure to find himself the subject of an FA probe over on-field comments after the European champions made a formal complaint about what are understood to have been interpreted as racist remarks during their defeat to Manchester United on Sunday.

The 37-year-old was also stood down from officiating for a week but it was the involvement of the police that would have been of most cause for concern.

The man behind the mooted black players' breakaway union, Peter Herbert, sent a letter to the Metropolitan Police Service (MPS), which read: "The Society of Black Lawyers wishes to record the incident that took place at Chelsea FC.

"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.

"Although this matter may be investigated by the FA, it is appropriate that the MPS independently see if a racially-aggravated offence has occurred."

The police confirmed they had received what they described as a "complaint" and were considering it.