Kosovo authorities say they have started digging next to a collapsed mine shaft searching for the bodies of more than 20 Serb civilians.
They are believed to have been killed by ethnic Albanian rebels in 1998. Arsim Gerxhaliu, Kosovo's top forensics official, said the site was unstable.
He said: "Some Serbian bodies have been buried during the war - this is all we know. Our job is to prove and to work on this information and to (find) if there is something inside or not."
The Serbs were believed to have been abducted by ethnic Albanian rebels and kept in a nearby mine, west of the capital Pristina.
Nato peacekeepers were also deployed to help local authorities investigate the site.
Around 1,000 people, both ethnic Albanians and Serbs, remain missing from the Kosovo War.