Human bones (Photo: INDRANIL MUKHERJEE/AFP/Getty Images)

Bone fragments from one of the biggest mass graves found in Sri Lanka since its civil war ended nearly a decade ago have been sent to the US for analysis, officials said Thursday.

The remains of dozens of men, women and children were found at the site in the northern Mannar district where Tamil guerrillas fought security forces during the conflict.

The fragments were sent with a forensic expert to a Miami-based laboratory this week to determine when those buried had died, a senior official from the Office on Missing Persons (OMP) said.

Establishing a timeframe would point to which forces were in control of the area at the time.

Tamil Tiger rebels and government forces both held the region at different times during the conflict, as did troops from neighbouring India, who were originally deployed as peacekeepers in 1987, but ended up fighting the Tigers until 1990 when they withdrew.

In a statement, the OMP said it expected a report from the US lab by the end of next month.

The mass grave in the former war zone was discovered in March last year by construction workers.

The OMP, which is independent of the government but has a state mandate, said just over 300 skeletal remains had been found so far, including the remains of about 20 children.

The office has wide powers to investigate cases of people still missing after the conflict and started work last year.

The report will determine whether the bones “are from one or multiple historical periods”, the OMP said.

Mannar was the scene of heavy fighting between government forces and the Tamil Tigers during the civil war that ended in May 2009.

A government-appointed panel said in 2013 that about 19,000 people were missing, including 5,000 security personnel, since the conflict began in 1972.

Both troops and Tamil rebels have been accused of targeting civilians.

(AFP)