Arsenal have launched an investigation into a video on social media that appeared to show fans using a racist insult towards Napoli defender Kalidou Koulibaly.
The video was filmed during last night's 2-0 win over Napoli in the Europa League quarter-final first leg.
An Arsenal statement said: "We utterly condemn use of this type of racist language and have launched an investigation to identify the culprit.
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"We operate a zero tolerance approach, and anyone behaving like this is not welcome at Arsenal and will be banned from matches.
"We have an extremely diverse community of fans who are all part of the Arsenal family and such incidents are rare at Emirates Stadium. We encourage supporters to report any incidents as they happen to stewards or via our matchday alert service."
The video appeared to come from the Instagram page of a home supporter and has subsequently appeared on Twitter.
The incident came on the same night in which Chelsea barred three people from attending their Europa League quarter-final away to Slavia Prague after video emerged of racist chants aimed at Liverpool forward Mohamed Salah in the hours before kick-off.
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It is not the first occasion Koulibaly has been the subject of racist abuse - Napoli asked to stop a game against Inter Milan on Boxing Day last year after fans reportedly made monkey chants in the direction of the Senegal international.
Speaking before Thursday's game on the racism storm that has engulfed football, Napoli head coach Carlo Ancelotti said: "When racism happens in Italy it is taken quite lightly, but in England it is a real scandal and only when we view this in the same light can we say that we are approaching the English model."
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