Football commentator and pundit Gary Neville blamed Boris Johnson’s election rhetoric on immigrants and immigration for fuelling the number of racist incidents in British society and sport.

Neville was speaking after the Manchester derby, which saw United defeat City 2-1. The result, however, was overshadowed by an incident during the second half of the game that appeared to show a City fan making a monkey gesture towards a United player.

Speaking on television afterwards, Neville linked the incident with the political leaders debate on the BBC on Friday evening.

“You are watching the prime minister’s debate where he is talking about migration to this country and people having to have certain levels. It fuels it all the time. It has got worse over the last few years in this country and not just in football,” said Neville, a former Manchester United and England international.

He added: “[This fan] thinks he can come to a game and racially abuse someone playing football. It is disgusting. It is terrible and something has to be done. It is not just about banning him from football. Everyone has a responsibility.”

He suggested English football has a greater responsibility after Gareth Southgate’s England team players were racially abused in Bulgaria earlier this year. “We always judge other countries on how they deal with racism but we are poor with dealing with it ourselves,” he said.

Manchester City said on Sunday night they were “aware of a video circulating on social media which appears to show a supporter making racial gestures” during the match.

The club also said they are “working with Greater Manchester Police in order to help them identify any individuals concerned”.

Manchester City said they operate a “zero-tolerance policy” regarding discrimination of any kind, adding that anyone found guilty of racial abuse will be banned for life.

They said they were also investigating an incident where objects were being thrown onto the pitch aimed at players.

After the game, United manager Ole Gunnar Solskjær spoke out strongly about the incident. “I’ve seen the video, heard from the players. We keep talking about it every bloody week. But he’s been caught on camera. He should, in my opinion, never be allowed into a football ground again. It is unacceptable.”

Manchester United made a formal complaint to the referee and their opponents after the game, it was revealed.

“I am sure that City and the authorities will deal with it. We keep talking about it every week and it doesn’t stop unless it’ll have consequences.”

Rival City manager Pep Guardiola said afterwards: “I support the statement the club has done. I am pretty sure the club and policemen are going to make the right decision for it not to happen again. Of course, it is a battle to fight every day, so unfortunately it happens in many places and hopefully it cannot happen again.”

Jesse Lingard, one of the United players at whom racist abuse was allegedly directed, said on social media last night: “Not even this idiot can ruin tonight’s feeling, shameful behaviour. It may be a derby but there is never ever a reason to be racist!”

Kick It Out, the campaign to rid football of racism, said last night it had been “inundated with reports of alleged racist abuse from a number of individuals at the Manchester Derby. We will be contacting both clubs to offer our support and hope swift action is taken to identify the offenders.”

The Professional Footballers’ Association condemned the alleged abuse: “We are disappointed by what appears to be racist abuse from fans at the Manchester derby. We welcome this prompt response from Manchester City. Racist abuse is a criminal offence and must be dealt with accordingly.”

League Two club Forest Green Rovers reported on Saturday night they were investigating a further incident of alleged racist abuse by a supporter of a player during their game with Scunthorpe United.