Chelsea have promised to take the "strongest possible action" against any supporters found to have sung an anti-Semitic chant in Budapest, just days after four fans were suspended for abusing Raheem Sterling.
Minutes into Thursday's Europa League clash with Vidi in Budapest's Groupama Arena, which ended 2-2, a vocal minority of Chelsea fans were heard singing a derogatory chant about Tottenham supporters, featuring anti-Semitic language.
Chelsea in January launched a campaign to raise awareness and educate fans about anti-Semitism in football and the club, including owner Roman Abramovich, who is Jewish, have expressed disgust at the latest incident.
"Anti-Semitism and any other kind of race-related or religious hatred is abhorrent to this club and the overwhelming majority of our fans," said a Chelsea spokesman.
"It has no place at Chelsea or in any of our communities.
"We have stated this loud and clear on many occasions from the owner, the board, coaches and players.
"Any individuals that can't summon the brainpower to comprehend this simple message and are found to have shamed the club by used using anti-Semitic or racist words or actions will face the strongest possible action from the club."
"We completely endorse the club's strong statement and would support them in any robust action which they now take against the perpetrators."