Manchester - Manchester City pledged to take a zero tolerance approach against supporters found to have subjected Manchester United players to racist abuse after the Premier League champions lost 2-1 to their local rivals on Saturday.
United midfielder Fred was hit by objects thrown from the crowd as he prepared to take a corner in the second half and footage on social media appearing to show a City fan mimicking a monkey at the Brazilian.
"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," City said in a statement.
"Officials from the Club are working with Greater Manchester Police (GMP) 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."