Colombo: Sri Lanka has failed to honour promises to investigate serious rights abuses and allegations that thousands of civilians were killed in the final stages of its ethnic war, a UN report says.

The report by human rights experts, which was submitted to the United Nations Human Rights Council (UNHRC) on Monday, found that investigations by local authorities were inconclusive and were not independent or impartial.

“The steps taken to investigate allegations of serious violations of human rights have been inconclusive, and lack the independence and impartiality required to inspire confidence,” according to the report.

The document, compiled by experts who visited Sri Lanka in September, asked the government to establish a “truth seeking mechanism” to address “transitional justice” in a country emerging from nearly four decades of ethnic strife.

It said grave human rights violations, including the killing of 17 aid workers of a French charity in August 2006, had not been probed despite government promises swiftly to bring perpetrators to justice.

There was also no transparency in alleged military investigations into claims of summary executions during the final stages of the war.

UN figures show that up to 100,000 people were killed between 1972 and May 2009, when security forces declared victory over Tamil Tiger separatists who had fought for independence for minority Tamils in the Sinhalese-majority state.

The bloody finale to the ethnic conflict drew international condemnation and sparked allegations that up to 40,000 civilians were killed by security forces in the last months of fighting, a charge Sri Lanka denies.