West Ham fans were heard to be singing offensive anti-semitic chants at Tottenham fans during Spurs' 3-1 victory at White Hart Lane on Sunday.
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Throughout the 90 minutes, large sections of the visiting support sang chants that were either anti-semitic or goading the violence some of the Spurs fans suffered during their trip to Rome for the Europa League game against Lazio on Thursday.
Targeting the home team's famous Jewish connections, the away fans made hissing sounds early in the first half, in relation to the concentration camps during the Second World War. Chants of 'Adolf Hitler's coming for you' were also sung.
Following the stabbing of a Spurs fan in Rome earlier this week, the West Ham supporters also chanted 'can we stab you every week?'
Despite the offensive chants, both managers were reluctant to initially condemn the incidents.
"I didn't hear it," West Ham manager Sam Allardyce said. "I don't hear what the fans say or do when I'm a manager concentrating on the game of football. They shouldn't be doing that but it's the least of my worries at the moment.
"Hitler? I never heard it. If I didn't hear it, I can't comment. They shouldn't be doing that but I don't want to be a political animal. I'm in here to talk about football."
Tottenham manager Andre Villas-Boas added: "It is difficult. You can interpret it in various ways. I prefer not to mar the performance with the situation like this. We know the animosity there is between Tottenham and West Ham. As long as it doesn't reach stupidity, it is a great, great rivalry between two London clubs.
"Although I understand your question, it would be extremely unfair of me to mar the performance of the players. But I understand the whole situation is unavoidable, although we can't decipher the complete meaning of what they were singing."
The Football Association is awaiting the officials' match report before deciding whether to act on the chants.