West Ham have said they are "disgusted" at a video apparently showing some of their fans singing anti-Semitic chants from a game near the start of last season.
The video appeared on social media on Monday evening and the club have responded by banning a supporter for life in relation to the footage.
The statement read: "We are disgusted by the contents of a video circulating on social media on Monday evening, filmed near the start of the 2018-19 season.
"We have taken immediate action to identify the offender and have subsequently handed our evidence to the Metropolitan Police.
"Additionally, the individual concerned will be banned for life from the London Stadium."
"The club is unequivocal in its stance – we have a zero-tolerance approach to any form of abhorrent behaviour.
"Equality and diversity is at the heart of the football club and we are committed to continue ensuring that everyone who enters the London Stadium is free to enjoy watching their team play football in an inclusive environment."
This comes after a joint investigation between Chelsea and Liverpool after a video emerged earlier this week of a Blues fan chanting alleged racist abuse towards Reds forward Mohamed Salah.
Meanwhile, a fan-funded anti-racism banner that shows solidarity with Moise Kean will be unveiled ahead of Everton's home meeting with Manchester City on Saturday evening, the Premier League club said.
The Italy international was subjected to racist abuse while playing for former club Juventus at Cagliari in April.
Everton fan group the County Road Bobblers raised more than £3,000 following a social-media campaign and, beyond funding a banner which will sport an image of summer signing Kean alongside the message 'No Al Razzismo (No To Racism)', donations will be made to anti-discrimination campaigners Kick It Out and to club charity Everton in the Community.
Fundraiser David Wycherley said: "When Moise Kean signed for us, Everton fans were delighted. I had followed Kean's progress in Serie A, and really felt for him when he faced racism on the pitch. I admired how well he dealt with it, especially for such a young player.
"It feels like he has come to the perfect place – The People's Club. He won't have to stand alone against racism – he now has hundreds of thousands of Blues around the world standing shoulder to shoulder with him."
