The United Nations has voiced concern at recent incidents of hate speech and incitement to violence in Bosnia and Herzegovina and in Serbia, fearing inflammatory acts will escalate ahead of elections this year.

Bosnian Serbs celebrated their national day on Sunday, marking the creation of the Republika Srpska (RS) – Bosnia’s Serb entity that was declared three decades ago.

It was one of the events seen as putting the country on the path to the war in Bosnia in the 1990s, which killed approximately 100,000 people and forced two million others from their homes.

In a statement on Friday, the spokeswoman for the UN High Commissioner for Human Rights said the UN was “deeply concerned” by incidents that saw individuals “glorify atrocity crimes and convicted war criminals, target certain communities with hate speech, and, in some cases, directly incite violence”.

Liz Throssell said people had chanted the name of convicted war criminal Ratko Mladic during torchlight processions, sung nationalistic songs calling for the takeover of locations in the former Yugoslavia and in one incident, individuals fired shots in the air outside a mosque.

Local media and victims’ associations highlighted that in Foca on Saturday several hundred people attended a fireworks display organised by Red Star Belgrade football supporters at which a large portrait of Mladic was unveiled on a building.

The former Bosnian Serb general was sentenced to life in prison for war crimes in Bosnia, in particular for the Srebrenica massacre and the siege of Sarajevo.

Serbia and Bosnia will hold elections in April and October, respectively, and Throssell warned that “continued inflammatory, nationalistic rhetoric” risked exacerbating an “extremely tense” political environment in 2022.

“These incidents – some in locations that saw large-scale atrocity crimes during the war in Bosnia and Herzegovina, such as Prijedor and Foca – are an affront to survivors, including those who returned to their homes after the conflict,” her statement read.

“The failure to prevent and sanction such acts, which fuel a climate of extreme anxiety, fear and insecurity in some communities, is a major obstacle to trust-building and reconciliation.”

Throssell’s comments came as Bosnia was facing its worst political crisis since the 1990s, after Bosnian Serbs blocked the work of the central government and Bosnian Serb leader Milorad Dodik threatened to withdraw from state institutions, including the army, the judiciary and the tax system.

The US-brokered Dayton Peace Agreement of 1995 ended three and a half years of war in Bosnia. The agreement also established Bosnia and Herzegovina as a state composed of two entities: a Bosniak-Croat-dominated federation and a Serb-run Republika Srpska.

Dodik is the Serb member of the tripartite Presidency of Bosnia and Herzegovina, and he has threatened the secession of Republika Srpska for 15 years.

His recent comments spurred fresh sanctions earlier this month from the United States, which accused Dodik of corruption and threatening the stability and territorial integrity of Bosnia and Herzegovina.

Dodik rejected the measures, saying the sanctions were “lobbied by several US officials who do not share the vision of Bosnia-Herzegovina that I have and which was signed in 1995”.