CHELSEA will give their full backing to police investigating an alleged racist gesture by a supporter towards a Manchester United player.
A picture appeared to show the fan making a "monkey" action during the Blues' League Cup fourth-round tie at Stamford Bridge.
Chelsea have also launched their own investigation into the matter in the hope of quickly identifying the person.
A statement from the club read: "The club will be examining all available footage and asks anyone who can identify the individual to contact the club.
"Chelsea FC is committed to removing all forms of discrimination and if we have sufficient evidence we will take the strongest possible action, including supporting criminal prosecution."
The Metropolitan Police confirmed they had opened proceedings after receiving a complaint.
A police statement read: "An investigation has been launched. There have been no arrests and enquiries continue."
The incident comes at a sensitive time for Chelsea, having lodged a formal complaint with the Football Association against referee Mark Clattenburg for using "inappropriate language" towards midfielder John Obi Mikel.
That matter is also being investigated by police. Clattenburg maintains his innocence.
Chelsea have been involved in a series of race-related issues over the past year.
In March the club banned a supporter for life after he admitted racially abusing former player Didier Drogba.
The most high-profile incident concerned captain John Terry, who is currently serving a four-match domestic ban after being found guilty of racially abusing QPR defender Anton Ferdinand by the FA.
It's understood the club are looking into a number of incidents concerning fans in the United section. One supporter ran onto the field and objects were thrown onto the pitch.
Chelsea won the match 5-4 after extra-time, in an extraordinary contest played just three days after United won a stormy Premier League clash between the clubs 3-2.
The games continue to come quickly for Roberto di Matteo's men with a trip to Swansea tomorrow -- the side's first domestic match outside London since August.