Colombo, Dec 30 (IANS): Sri Lankan authorities are investigating a new mass grave found in the island nation's northern area, which was once under rebel control, police said.

Police spokesman Ajith Rohana said that the excavation work was carried out at the mass grave in Mannar in presence of the authorities, Xinhua reported Monday.

The grave site which was stumbled upon this month had at least 10 human skeletal remains buried inside, following which an investigation and forensic examinations were being carried out.

The police suspects the grave was used by the Tamil Tiger rebels during the war to bury civilians and soldiers killed by the rebels.

The Tamil Tigers controlled most parts of the north including parts of Mannar for nearly 30 years. The Sri Lanka army defeated the Tamil Tiger rebels in May 2009

The discovery of the grave in Mannar comes even as Sri Lanka investigates another mass grave found in Matale, in central Sri Lanka.

Over 150 skeletal remains and human bones were unearthed from the mass grave in Matale late last year. Forensics had determined that the remains were of those killed sometime in the late 1980s.