Ghana midfielder Alfred Duncan has spoken out after Napoli defender Kalidou Koulibaly was allegedly subjected to racist chants during his side’s Boxing Day defeat at Inter.

A number of high-profile players, including Juventus' CristianoRonaldo and Inter captain Mauro Icardi, have posted messages of support for Koulibaly while also condemning racism.

Duncan has followed suit and called for stiffer punishment for the perpetrators to ensure the canker is eradicated from sports.

“I think the League must punish episodes like those in Milan. These are bad things to see in football.”

Inter have been ordered to play their next two home matches behind closed doors, with head coach Luciano Spaletti, Napoli coach Carlo Ancelotti and UEFA all condemning the abuse.

Koulibaly was sent off after picking two late bookings, one for a shirt pull and the second for sarcastically clapping the referee's decision.

Napoli fans showed their support of Koulibaly with banners and wearing masks of the Senegalese defender's face during their 3-2 win over Bologna on Saturday.