Red Star Belgrade fans unveiled a tifo of war criminal Ratko Mladic before their derby win over Partizan Belgrade on Sunday night.
Mladic, who died in a United Nations prison in August, was given a life sentence for genocide, war crimes and crimes against humanity in 2017.
He and his troops were responsible for the systematic killing of the non-Serb population of Bosnia-Herzegovina during the wars in the former Yugoslavia between 1992 and 1995.
He oversaw the massacre of 8,000 men and boys at Srebrenica and a siege of the capital Sarajevo in which more than 10,000 people died.
Red Star have already been fined 90,000 euros (£77,000) this season by Uefa, external after their fans unveiled a banner commemorating Mladic in a Europa League play-off against Czech side FC Viktoria Plzen last month.
Red Star’s social media accounts published a video of the tifo and the two teams observing a minute’s silence for Mladic, alongside a saluting emoji.
The official X account of Bosnia-Herzegovina’s national team replied with an obscenity.
After initially enjoying the protection of Serb president Slobodan Milosevic, who would later die while on trial for genocide himself, Mladic spent more than a decade on the run, eventually being found hiding out in a remote farmhouse.
However, he remains a celebrated figure for some in Serbia with thousands gathering at a church in Belgrade for his funeral on Monday., external