Manchester City have released a statement, condemning racial gestures made towards Manchester United midfielder, Fred, during their 2-1 loss in the Derby on Saturday.
Fred suffered abuse and was stoned with objects, as he stepped up to take a corner kick, with United two goals up.
City's statement read: "Manchester City FC are aware of a video circulating on social media which appears to show a supporter making racial gestures during the second half of the match against Manchester United this evening.
"Officials from the Club are working with Greater Manchester Police in order to help them identify any individuals concerned and assist with their enquiries.
"The Club are also working with GMP regarding an instance of objects being thrown onto the field of play.
"The Club operates a zero tolerance policy regarding discrimination of any kind, and anyone found guilty of racial abuse will be banned from the club for life."