The Football Association is set to investigate apparent anti-Semitic abuse by West Ham fans towards Tottenham supporters at White Hart Lane.
An FA spokesman said it was "likely" that the governing body would launch a formal investigation once the match officials' reports had been received.
Hammers fans appeared to mock the gassing of Jews in the Holocaust as Spurs supporters were allegedly subjected to a second dose of anti-Semitic abuse in the space of four days.
Just a matter of days after Ashley Mills was stabbed before 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.