Two West Ham fans were arrested during their 3-3 draw with Brighton at the London Stadium on Saturday after they allegedly made homophobic gestures.
Another male West Ham fan has been arrested on suspicion of common assault according to the Metropolitan Police.
The two fans arrested for alleged homophobic gestures have been released but are under investigation.
"Two male West Ham fans were arrested on suspicion of making homophobic gestures," a Metropolitan Police spokesperson told BBC Sport.
"One male (also a West Ham fan) was arrested on suspicion of common assault.
"They were taken to east London police stations where they were subsequently released under investigation. Enquiries continue."
A club statement read: "West Ham United is disgusted to hear of alleged homophobic incidents at the game against Brighton & Hove Albion. The matter is now with the police but anyone found guilty of acting in a discriminatory manner will be banned for life from London Stadium and from travelling with the club.
"The club is unequivocal in its stance - we have a zero-tolerance approach to any form of discrimination. Equality and diversity is at the heart of the football club and we are committed to continue ensuring that everyone who enters London Stadium is free to enjoy watching their team play football in an inclusive environment."
The Hammers also put out a statement earlier this season in which they said the club "in no way condones" homophobic behaviour following an incident against Chelsea at Stamford Bridge on December 2.
Homophobic incidents have not been uncommon in England's top four divisions this season with the Premier League and the EFL doing everything they can do address the issue.
Back in January referee Keith Stroud halted a game between Millwall and Reading at the Den for alleged homophobic chanting, but an internal club investigation found "no evidence".
The incident at the London Stadium is not the first time Brighton have been involved in such matters after one away fan and two home supporters were arrested during their draw with Chelsea at the Amex Stadium on New Year's Day.
While back in August Bristol Rovers were fined £7,500 and ordered to take action after some of their fans directed slurs at Brighton fans during a Carabao Cup clash.
