Bosnian Serb authorities have for the first time handed over a war crimes suspect to the international tribunal sitting at The Hague.
Savo Todovic surrendered and was then flown to The Hague, where he was handed over to court officials.
Mr Todovic, 52, was a commander at the Serb-run Foca camp where many Muslims died during the Bosnian conflict from 1992 to 1995.
Several wartime Bosnian Serb leaders are wanted by The Hague tribunal.
Bosnian Serb authorities have been persistently criticised by the international community for failing to cooperate with The Hague tribunal.
The tribunal's most wanted men - former Bosnian Serb military and political leaders Ratko Mladic and Radovan Karadzic - remain at large and are believed to be in the Bosnian Serb republic.
The Bosnian Serb news agency Srna quoted a police official as saying: "On the territory of the Republika Srpska, Savo Todovic, originally from Foca (in eastern Bosnia), indicted by the UN war crimes court, surrendered voluntarily to the interior ministry."
It said Bosnian Serb Interior Minister Darko Matijasevic was accompanying Mr Todovic to The Hague.
The International Criminal Tribunal for the former Yugoslavia has charged Mr Todovic with crimes against humanity and war crimes allegedly committed during his time at the Foca camp, from 1992 to 1993.
According to indictment, Mr Todovic selected detainees for beatings, interrogations, punishments and execution.
Hundreds of inmates at the camp remain unaccounted for.