West Ham today vowed to take the "strongest possible action", including life bans for any fans found guilty of anti-Semitic chants at Tottenham.
The English Football Association is set to investigate apparent abuse where Hammers fans yesterday appeared to mock the gassing of Jews in the Holocaust.
West Ham said in a statement: "West Ham United are in contact with Tottenham Hotspur to assist them with their investigation into the conduct of a small number of supporters and alleged inappropriate chanting during yesterday's match at White Hart Lane.
"West Ham United will take the strongest possible action against any of their supporters, including enforcing life bans from the club, that are found guilty of behaviour which is categorically not condoned by West Ham United.
"During the 46 games in the Championship last season, West Ham United had zero arrests for racism or violence, so while we are surprised to see such reports today, we will examine any available evidence of such conduct thoroughly and take the appropriate action."
An FA spokesman said it was "likely" that the governing body would launch a formal investigation once the match officials' reports had been received.
The reported abuse came just days after Spurs fan Ashley Mills was stabbed ahead of Thursday's Europa League game in Rome.
West Ham supporters sang 'Viva Lazio', 'Can we stab you every week?' and hissed on several occasions, apparently mocking the mass execution of Jews during the Second World War.
There were also reportedly chants about Adolf Hitler during the match, which Spurs won 3-1.