The suspect, Sredoje Lukic, who has been hiding since late 1990s, was indicted by the tribunal in The Hague, Netherlands, in 2000 for crimes against humanity, Rasim Ljajic, Serbia-Montenegro's minister in charge of cooperation with the tribunal, said on Tuesday.
"Sredoje Lukic surrendered as the result of a joint action by Serbian and Bosnian Serb authorities," Ljajic said. "He will be extradited to The Hague from Bosnia."
Sredoje's cousin Milan Lukic, also charged with war crimes during the 1992-1995 Bosnian war, was arrested in Argentina in August and was awaiting his extradition to the UN tribunal.
The two were members of the notorious Bosnian Serb paramilitary group called the Avengers, which fought Bosnian Muslims in eastern Bosnia during the war, according to the war crimes indictment against them.
They organised the paramilitary group which between May 1992 and October 1994 "committed, planned, instigated and ordered the executions" of Bosnian Muslims on the territory of Visegrad and elsewhere in the Bosnian Serb-controlled territory, the indictment says.
Sredoje Lukic is charged with cruel and inhuman acts against non-Serbs, persecution on political racial and religious grounds, crimes against humanity as well as unlawful detention, humiliation, terrorising and psychological abuse of Bosnian Muslims.
"Sredoje Lukic surrendered as the result of a joint action by Serbian and Bosnian Serb authorities. He will be extradited to The Hague"
In June 1992, according to the indictment, the Lukic cousins and others led seven Bosnian Muslim men to the Drina River and forced them to line up along its bank where they opened fire on the men with automatic weapons, killing five.
Also in June, the Lukics and others drove to a furniture factory in Visegrad, where they forced seven Bosnian Muslim men to go to the bank of the river by the factory. They then shot and killed seven of them, the indictment says.
Sredoje Lukic is the 15th Serb war crimes fugitive to surrender to the Serbian authorities since October last year. The Serbian government is under huge Western pressure to cooperate with The Hague tribunal in exchange for the country's access to the European Union and Nato.
But the two top war-crimes fugitives, wartime Bosnian Serb leader Radovan Karadzic and military commander General Ratko Mladic, remain at large.