Serbian authorities have discovered a mass grave that may contain as many as 250 bodies of ethnic Albanians believed to have been killed during the 1998-99 conflict in Kosovo, according to Reuters. Serbia's war crimes prosecutor quoted witnesses as saying the corpses were buried under an office building in Rudnica, in southern Serbia, close to neighbouring Kosovo. Kosovar officials have been pressing Serbia to continue to look for bodies moved to the area by Serbian forces trying to cover up killings of majority ethnic Albanians in Kosovo, then waging a guerrilla war against Belgrade. Kosovo, a former province of Serbia, came under U.N. administration after NATO intervened with a bombing campaign in 1999 to halt Yugoslav ethnic cleansing. It declared independence in 2008. "According to eyewitness testimonies, the site contains 250 bodies of Kosovo Albanians," prosecutor Vladimir Vukcevic told a news conference. He could not give any details of who the eyewitnesses were. The European Union's law and order mission in Kosovo, EULEX, said it had helped Serbia with information and intelligence. "But we are still waiting for confirmation if the site has indeed been located," it said in a statement. Kosovo Deputy Prime Minister Rame Manaj said Belgrade had been repeatedly asked to check the site. U.N. PROSECUTOR TO VISIT "This is evidence that Serbia was the perpetrator of the crime and was trying to hide its crimes, but they cannot hide them for ever,"Manaj told Reuters. "We have information on another mass grave near the town of Medvedja in southern Serbia," Manaj said, adding there were still another 1,860 people missing, including around 400 Serbs and other non-Albanians. This was the sixth mass grave found since 2000. The largest, containing the bodies of more than 800 Kosovo Albanians, was found in 2001 in pits at a police training ground outside Belgrade. Vukcevic said the mass grave discovery was a sign that Serbia was decisively dealing with its past and was committed to "investigating each crime regardless of who committed it." "This is the best way towards reconciliation in this region," Vukcevic said. "This is our obligation towards the victims and their families...Our goal is that justice be served for the victims." Chief U.N. war crimes prosecutor Serge Brammertz is due to arrive in Belgrade on Wednesday to discuss Serbia's progress in cooperation with the international criminal tribunal for the former Yugoslavia in The Hague. A positive report from Brammertz would pave the way to ratification of a Stabilisation and Association Agreement between the EU and Serbia, a stepping stone towards membership of the bloc. Progress hangs on whether Serbia arrests and hands over fugitive Bosnian Serb wartime commander Ratko Mladic, charged with genocide by the U.N. war crimes tribunal. Brussels also expects from Belgrade a more constructive stance on Kosovo. Serbia refused to recognise its 2008 independence declaration and has sought a ruling from the International Court of Justice on the issue. Vukcevic's spokesman Bruno Vekaric told the news conference the prosecutor's office was now in the process of obtaining approvals and gathering funds for exhumation of the bodies.