Srebrenica victims will be buried at the memorial on 11 July

The discovery was made after a tip-off from European Union peacekeepers, a Bosnian Serb police spokesman said.

"In the early morning hours we found a certain amount of explosives at two separate locations inside the memorial centre," spokesman Radovan Pejic said.

In July 1995, about 8,000 Muslim men and boys were killed at Srebrenica.

They were separated from their families and massacred, in the worst atrocity in Europe since World War II.

Bosnian Serb forces carried out the killings after overrunning the eastern Bosnian town, which the UN had declared a "safe area".

Massacre video

The continuing freedom of the men accused of ordering the massacre - Bosnian Serb leader Radovan Karadzic and his military commander, General Ratko Mladic - has cast a shadow over the forthcoming anniversary commemorations, scheduled for 11 July.

The two men are wanted by the United Nations war crimes tribunal at The Hague, but remain on the run.

Last month a video emerged showing a group of Muslim teenagers being killed at Srebrenica in 1995.

The footage showed six teenage boys, their hands bound, being led from a truck and shot in the back.

The video was shown at the trial of former Serbian leader Slobodan Milosevic at The Hague.