( CNN ) -- English football 's battle to eradicate racism suffered another blow on Thursday as police launched an investigation into allegations that a Chelsea supporter made a racist gesture towards a Manchester United player . A photo of the fan making a `` monkey '' action , which appeared to be targeted at United 's Danny Welbeck during a League Cup match that Chelsea won 5-4 , was published in a British newspaper Thursday . Chelsea has launched its own investigation into the matter and has already promised to assist the police in any way possible . A statement from the Metropolitan Police read : `` Today , Thursday , November 1 , police have received a complaint regarding alleged racist behavior at Stamford Bridge last night , Wednesday , October 31 . `` An investigation has been launched . There have been no arrests and enquiries continue . '' The incident follows Chelsea 's claim that a referee made racial comments to one of the club 's players during Sunday 's 3-2 home defeat by United -- a controversial match in which the Premier League-leading team had two men sent off . Chelsea lodge Clattenburg complaint . On Wednesday , Chelsea confirmed it had lodged a formal complaint with the Football Association after alleging that official Mark Clattenburg had used `` inappropriate language towards John Obi Mikel . Now the club has stated that it will take `` the strongest possible action '' against the supporter involved in Wednesday 's incident . `` Chelsea Football Club can confirm we are investigating an incident involving a member of the crowd at last night 's game against Manchester United , '' a spokesman said . `` 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 . '' Police to investigate 'racist ' referee in Chelsea case . Chelsea banned a supporter for life in March after finding them guilty of racially abusing the club 's former striker Didier Drogba . Club captain John Terry is currently serving a four-match domestic suspension after the FA found him guilty of racially abusing Queens Park Rangers defender Anton Ferdinand despite the former England international having been earlier cleared in court .
Police launch investigation into allegations of `` racist gesture '' by Chelsea supporter . Supporter photographed in British national newspaper making alleged gesture . Manchester United striker Danny Welbeck appeared to be the target of alleged abuse . Comment: