Ole Gunnar Solskjær said that the Manchester United players Fred and Jesse Lingard were shaken up during the 2-1 derby victory at City by an incident of racist abuse.

City have launched an investigation after a video clip appeared to show a home supporter making a monkey gesture. Fred had been hit by an object thrown from the crowd as he went to take a corner midway through the second half and Lingard was also close by.

“I’ve seen it on the video – Fred and Jesse in the corner taking coins from the City fans first of all, and then there’s this not-so-intelligent fella chanting racist abuse towards my two players,” Solskjær, the United manager, said. “We talk about it every bloody week. He [the fan] has been caught on camera. He should never be allowed into a football ground again. Unacceptable. I am sure the authorities will deal with it.

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“We talk about it every week. It doesn’t stop them unless it has consequences. It has affected both of them. They are in the corner. Sometimes you feel sorry for these people. It is an act of ignorance. It is not City’s fault. It is his. Why don’t we educate him?”

City confirmed they were reviewing the incident, saying: “We are aware of a video circulating on social media which appears to show a supporter making racial gestures during the second half.

“Officials from the club are working with Greater Manchester Police in order to help them identify any individuals concerned and assist with their inquiries. The club are also working with GMP regarding objects being thrown on to 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.”

Marcus Rashford said he had not been aware of the racist abuse during the game. The United forward added: “But it can happen. I think in recent times we have been dealing with it a bit better but the fact is it is still happening. It isn’t good enough so there is still work to do.”

Gary Neville, working on Sky Sports, agreed with Jamie Redknapp that racism was a societal and not just a football problem. The former United defender drew attention to Boris Johnson’s remarks on migration during the prime minister’s debate with Jeremy Corbyn on Friday, saying that comments such as these have “fuelled” the rise in racist incidents in recent years.