Nearly 8,000 people were killed in Sri Lanka's war-torn north during the government's final offensive to crush the Tamil Tiger rebels, Colombo's census department said on Saturday.
The figure is in stark contrast to estimates by international rights groups, which say up to 40,000 civilians perished in the final months of the civil war and have heavily criticised Sri Lanka's actions at the end of the conflict.
The 80-page census report said 11,172 people were reported dead in the former war zone in 2009, at the height of fighting between government forces and the separatist Liberation Tigers of Tamil Eelam (LTTE), with only 2,523 due to natural causes.
It described 7,934 deaths as being due to "extraordinary circumstances", but did not identify those responsible or whether Tiger combatants were included in the statistics.
The cause of death was "not stated" in the balance of 715 deaths, the department said.
Colombo has long maintained that its military should not be held culpable for any civilian deaths during the fighting, blaming the Tigers for using non-combatants as human shields.
But last week the military appointed a five-member panel of senior army officers to probe allegations of war crimes by its own troops in the final phase of fighting.
The census department said the highest concentration of 2009 deaths was in Kilinochchi district, where the rebels had their de facto capital, and adjoining Mullaittivu, where the final battle was fought in May of that year.
The findings were based on a census carried out between June and August last year and were dated November 2011, but only released on Saturday.
Sri Lanka's rights record is expected to be discussed at a UN Human Rights Council meeting opening in Geneva next week where the US has said it will bring a resolution demanding the island probe alleged war crimes by its troops.
The United Nations has estimated that up to 100,000 people died in the conflict between 1971 and 2009.