United Nations rights chief Navi Pillay on Wednesday warned Sri Lanka to show clear progress towards reining in rights abuses and investigating suspected war crimes by next March, or face an international probe.
Pillay called on Colombo to use the time left before she delivers a widely-anticipated report on the country to the UN Human Rights Council next March "to engage in a credible national process with tangible results, including the successful prosecution of individual perpetrators."
Were that not to happen, she warned in an interim report presented to diplomats in Geneva by her deputy Flavia Pansieri, "the international community will have a duty to establish its own inquiry mechanisms."
In March 2012 and March 2013, the UN's highest human rights body adopted resolutions calling on Sri Lanka to investigate allegations of widespread violations committed during the final months of a 37-year Tamil separatist war that ended in 2009, but has so far stopped short of calling for an international investigation.
Sri Lanka, which maintains it is making great strides in its national reconciliation process, flatly rejected the suggestion an international probe might be needed.
Pillay has "no mandate to make such a claim," Sri Lankan ambassador to the UN, Ravinatha Aryasinha, told the assembly of diplomats, insisting his government had put in place "multiple mechanisms to address accountability."
The UN estimates that up to 100,000 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 Tamil Tiger rebels.
Sri Lanka has rejected the charges and maintains that its troops did not kill a single civilian.
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.
Washington agrees that Sri Lanka has so far shown little progress "with respect to what is relevant to accountability for the past," US ambassador to the Human Rights Council, Eileen Chamberlain Donahoe, told AFP on the sidelines of the assembly.
"We agree with the High Commissioner that if there is no domestic progress on accountability, the call for an international investigation is warranted," she said.
Pillay also lamented the erosion of rule of law in Sri Lanka, and said the controversial impeachment of the country's chief justice earlier this year had "shaken confidence in the independence of the judiciary and separation of powers in general."
This was especially worrying in light of a "recent surge in incitement of hatred and violence against religious minorities, including attacks on churches and mosques," she said.
Pillay knew of 229 such incidents between January and July this year alone.
"Regrettably, government interlocutors (seem) to downplay this issue or even put the blame on minority communities themselves," she said.
She also described high levels of harassment and intimidation of human rights advocates, lawyers and journalists, pointing out that a number of the people she met in Sri Lanka had been interrogated by the military or police before and after her visit.
Aryasinha harshly criticised Pillay's report, rejecting her "unsubstantiated claims" that the rule of law and democratic institutions were being undermined, and insisting other charges "lack credibility" or were "baseless and disingenuous."
"Sri Lanka needs to be encouraged, not impeded," he said.