Anyone who denies the "Srebrenica genocide" has no place in Europe, an EU spokesman said on Tuesday, ahead of a likely vote at the UN to declare July 11 an international day to remember the massacre.
It comes after EU leaders agreed in March to open talks with Bosnia on joining the bloc, with tensions rising in recent weeks in the Balkans as thousands of ethnic Serbs in Bosnia rallied against the initiative.
Politicians in Serbia and ethnic Serbs in Bosnia have largely tried to play down the incident, with many refusing to call it a genocide -- including the leader of the Bosnia's Serb entity Milorad Dodik.
No date has been set for a vote on the resolution.
On Tuesday, EU spokesperson for Foreign Affairs Peter Stano said the bloc's position on Srebrenica remained "very clear".
"There is no question about the fact that there was genocide in Srebrenica. There cannot be any denial," Stano told reporters, citing a 2007 ruling by an international court on the matter.
"And anyone trying to put it in doubt has no place in Europe," he added.
Negotiations on Bosnia joining the EU will only begin in earnest once the Balkan country has passed more key reforms.
Bosnian Serb forces captured Srebrenica -- a UN-protected enclave at the time -- on July 11, 1995, a few months before the end of Bosnia's bloody civil war, which saw approximately 100,000 people killed.
In the following days, around 8,000 Muslim men and teenagers were killed by Bosnian Serb forces -- a crime described as genocide by international justice.
The incident is largely regarded as Europe's worst single atrocity since World War II.
Serbian President Aleksandar Vucic this week said he planned to travel to the United Nations to express his country's position ahead of a vote on the resolution.
"Someone has to give a response to those who would like to accuse the Serbs of being a genocidal people, and I will give them the response they deserve," he told reporters in Belgrade.
Former Bosnia army chief Ratko Mladic -- who was sentenced to life in prison by an international tribunal for war crimes, including his role in Srebrenica -- remains praised by politicians in both Serbia and Bosnia's Serb entity.