12/14/2012 03:44 EST | Updated 02/12/2013 05:12 EST

Workers find 49 human skulls in possible mass grave at construction site in Sri Lanka

COLOMBO, Sri Lanka - Workers have discovered a possible mass grave with 49 human skulls during two weeks of excavations on a construction site in central Sri Lanka.

Police spokesman Prishantha Jayakody said Friday the skulls plus other bones were found during excavation work for an extension on a hospital in Matale town.

Jayakody said other details about the bones and the burial site were immediately not known.

But the People's Liberation Front, a Marxist group that carried out two armed insurrection since 1971, called for an investigation to see if the site is a mass grave where its members were buried after being killed by government soldiers.

The group's clashes with government troops left heavy casualties on both sides.