Sri Lanka has rejected United Nations Rights Chief Navi Pillay’s call for an international probe if it fails to show clear progress by next March in probing alleged war crimes during the three-decade long conflict with LTTE.

Sri Lanka’s Ambassador to the U.N. in Geneva, Ravinatha Aryasinghe, said on Wednesday that Ms. Pillay has “no mandate to make such a claim”. He insisted that his government had put in place “multiple mechanisms to address accountability.”

“Sri Lanka needs to be encouraged and not impeded,” Mr. Aryasinghe said.

Ms. Pillay yesterday called on Colombo to use the time left before she delivers a widely-anticipated report on the country to the U.N. Human Rights Council next March “to engage in a credible national process with tangible results, including the successful prosecution of individual perpetrators.”

In March 2012 and March 2013, the U.N.’s highest human rights body adopted resolutions calling on Sri Lanka to investigate allegations of widespread violations committed during the final months of the conflict that ended in 2009.

Ms. Pillay, who conducted a fact-finding trip to Sri Lanka last month, said she had received “little new information about the courts of inquiry appointed by the army and navy to further investigate the allegations of civilian casualties and summary executions” towards the end of the civil war.

The U.N. estimates that up to 1,00,000 people died during the conflict between 1972 and 2009, and rights campaigners claim 40,000 civilians were killed in the final military offensive in 2009 that crushed the LTTE rebels. The Sri Lankan government has rejected these charges.