Police have launched a probe into footage that emerged on social media of what appear to be West Ham fans singing anti-Semitic chants before their match with Tottenham.
Footage was uploaded to Twitter by Spurs fan @RomanGeezer, who Tweeted: "On the train on the way to the game, West Ham fans break into song in Stamford Hill, a Jewish area, scum."
Tottenham fans have a strong association with the Jewish community and have been targeted in the past with anti-Semitic abuse, and this latest incident comes after a week in which the football world has been striking out against racist fans.
Two incidents involving Chelsea fans travelling for their Champions League match with PSG involved racist chanting, one at St Pancreas station, and one which was filmed, where Chelsea fans top a black man boarding a Paris Metro train.
A British Transport Police (BTP) spokesman said: "We are encouraged the public has the confidence to report incidents of inappropriate and offensive football-related behaviour to us."
"We take these incidents very seriously, and it is clear what happened on the Paris Metro and at St Pancras the following night were not isolated events."
Tottenham said it hoped those involved would be identified and dealt with seriously.
A spokesman for the club said: "Anti-Semitism in any form is wholly unacceptable and we support all efforts to kick it out of the game."
"We hope that those individuals responsible for this vile behaviour are identified and dealt with in the strongest way possible."
The game itself between Spurs and West Ham ended 2-2 after Harry Kane grabbed a late equaliser in stoppage time.