Tottenham manager Mauricio Pochettino was angered by the "unacceptable" anti-Semitic banner displayed by Partizan Belgrade fans in their Europa League opener.
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A much-changed Spurs side got their Group C campaign off to a sturdy start by securing a hard-fought, 0-0 draw in an intimidating atmosphere in the Serbian capital.
It was a solid performance overshadowed by an anti-Semitic banner in the home end.
UEFA is investigating the issue pointed out to them by Tottenham officials, with a delegate from the governing body taking photographic evidence after the match.
"I didn't see it," Spurs boss Pochettino said. "The club is aware but I did not see [it myself].
"But if this is true, then it is an unacceptable thing. It is very disrespectful.
"This is a shame, very disrespectful and unacceptable."
Partizan were thrown out of the UEFA Cup and fined in 2007 for rioting during a first qualifying round first-leg clash at Zrinjski Mostar.
Thursday's incident came two years on from the racial abuse suffered by England under-21s in a European Championship play-off in Serbia.