Seven former soldiers of the Bosnian army were arrested on Friday, suspected of having killed 20 Bosnian Serb civilians during the country's 1992-95 war, the prosecutor's office said.
The seven are suspected of attacking a group of Serb civilians in eastern Bosnia, killing mostly women, children and elderly people fleeing fighting in the area, said a statement from the war crimes prosecutor's office.
The crime was described by the Bosnian prosecutor as "the worst wartime killing of Serbs in eastern Bosnia."
The inter-ethnic war in Bosnia claimed around 100,000 lives and led to some two million refugees and displaced people, almost half of the former Yugoslav republic's pre-war population.
Bosnia set up a war crimes prosecutor's office and court in 2005 to assist the UN's International Criminal Tribunal for the former Yugoslavia in The Hague by dealing with lower-level cases on a national basis.
So far, the local court has closed 110 cases, handing down several hundred guilty verdicts.