The remains believed to belong to at least 19 victims of the 1995 Srebrenica massacre have been exhumed from a mass grave in eastern Bosnia, an official said on Friday.

- So far we have exhumed six complete and 13 incomplete skeletons - Lejla Cengic of Bosnia's Missing Persons Institute told AFP.

The victims' hands had been tied with wire and two had been blindfolded, she added.

Forensic experts expect to find more bodies in the grave located in a 30-meter (99-foot) deep natural cave in the village of Bisina, near the eastern town of Tuzla.

Bullet casings found on the site indicate that the victims had been executed over the cave, Cengic said.

Bosnian Serbs overran the UN-protected Muslim enclave near the end of Bosnia's 1992-1995 war before summarily killing around 8,000 Muslim men and boys within a few days.

The remains of thousands of the massacre victims have been exhumed over the past years from about 70 mass graves around the ill-fated town, with more than 5,600 people identified by DNA analysis.

The Srebrenica massacre is considered the worst atrocity in Europe since World War II. It is the only episode of Bosnia's war that has been ruled as genocide by the International Criminal Tribunal for the former Yugoslavia (ICTY) and the International Court of Justice (ICJ), both based in The Hague.

The trial before the ICTY of the Srebrenica massacre's alleged mastermind, Bosnian Serb wartime leader Radovan Karadzic, is due to start on Monday.

Karadzic was arrested in Belgrade in July 2008 after 13 years on the run.

His military commander Ratko Mladic, also indicted by the ICTY in connection with Srebrenica, remains on the run and is believed to be hiding in Serbia.