(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.
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Police launch investigation into allegations of "racist gesture" by Chelsea supporter
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Supporter photographed in British national newspaper making alleged gesture
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Manchester United striker Danny Welbeck appeared to be the target of alleged abuse
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Chelsea promise to "take the strongest possible action, including criminal prosecution"
"Chelsea Football Club can confirm we are investigating an incident involving a member of the crowd at last night's game against @placeholder," a spokesman said.