By Maja Zuvela
SARAJEVO (Reuters) - Organizers of the 20th anniversary commemoration of the Srebrenica massacre in Bosnia threatened on Tuesday to call off the event unless Swiss authorities release the region's Muslim wartime defender.
July 11 marks 20 years since more than 8,000 Muslim men and boys were massacred by Bosnian Serb forces in the Srebrenica area toward the end of the 1992-95 Bosnian war, in the worst mass killing on European soil since World War Two.
But the arrest in Switzerland last week of former Bosnian army commander Naser Oric, on a Serbian warrant issued last year, has cast a shadow over the event and thrown into doubt the planned attendance of Serbian Prime Minister Aleksandar Vucic.
Serbia accuses Oric, a hero to many Muslim Bosniaks for organizing the defense of Srebrenica against Bosnian Serb forces, of war crimes against ethnic Serbs in the region. He was acquitted of war crimes by a United Nations court in 2008.
On Tuesday, the organizing committee of the Srebrenica anniversary said Oric's detention may force the postponement of the event and the burial of remains recently exhumed and identified.
"We will wait for another week ... and then we'll decide whether the bural and other activities will be held," Srebrenica's mayor and head of the committee Camil Durakovic said, according to Bosnia's Fena news agency.
He said the committee could not guarantee security for the event under such circumstances.
"We call on state authorities to make direct contact with their Swiss counterparts, because this is more a political than a legal issue," he said. "We cannot wait for July 11 with Oric held there."
Serbia said on Sunday it had filed an official extradition request with the Swiss authorities. On Monday, the Bosnian prosecutor's office said it too had sought Oric's return to Bosnia, saying his extradition to Serbia would jeopardize a separate legal case against him in Bosnia.
(Writing by Matt Robinson; editing by Andrew Roche)