Police are investigating a complaint after footage of anti-Semitic chanting at Upton Park appeared on the internet.
West Ham have already launched their own investigation into claims that some of their fans engaged in racist chants before Sunday's defeat to Tottenham.
A police spokesperson said: "The Public Order Branch Football Unit is investigating a complaint of an anti-Semitic video on an internet site.
"It appears to have been made at the West Ham v Tottenham match on 4 March."
The video clip has since been removed from the internet at the request of police.
West Ham said in a statement: "We are a leading campaigner in the Kick Racism out of Football campaign.
"We will not tolerate racist behaviour. We will investigate this matter fully."
The Football Association passed footage of the alleged incidents to police and asked the club to provide CCTV images.
An FA spokesman added: "Racist behaviour has no place in football. We would hope that, if these individuals are identified, they will be issued with banning orders."