Chelsea will give its full backing to police investigating an alleged racist gesture by a supporter towards a Manchester United player.
A picture published in the national press appeared to show the fan making a "monkey" action during the Blues' Capital One Cup fourth-round tie at Stamford Bridge.
Chelsea has also launched its 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."
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
That matter is also being investigated by police. Clattenburg maintains his innocence.
Australia's triumphant Socceroos have celebrated booking a place in next year's 2014 FIFA World Cup in Brazil with hundreds of fans in Sydney on Wednesday.