Imprisoned Tamil Tiger rebels told the investigators that the grave, about fifteen kilometres from Kilinochchi, contained the remains of twenty-six army and navy personnel, allegedly taken prisoner and then shot dead by the insurgents.

Cremated

A military spokesman Major General Ubaya Medawela, told the BBC the men were then apparently cremated, their ashes thought to be buried underground.

"The information we have is that these security personnel were shot dead, cremated and their ashes were buried in a mass grave," said the military spokesman.

He said it was the first case of a suspected mass grave containing government troops since the end hostilities.