Sri Lanka accused the United Nations rights chief on Tuesday of "unwarranted interference" by calling for an international inquiry into allegations that troops killed thousands of civilians at the end of the civil war.
The government of President Mahinda Rajapakse formally rejected the demand by UN High Commissioner for Human Rights Navi Pillay for an external investigation into what she called "credible allegations" that 40,000 ethnic Tamil civilians were killed by Sri Lankan forces in 2009.
Pillay's recommendation to a UN Human Rights Council (UNHRC) meeting in Geneva next month "reflects bias and is tantamount to an unwarranted interference in the internal affairs of a sovereign state", Colombo said in a statement.
The United States has already said it will move a third censure motion against Sri Lanka at the UNHRC, buttressing the recommendations of Pillay, who visited Sri Lanka on a week-long fact-finding mission last August. Shortly before leaving the island, she launched a scathing attack on Sri Lanka's failure to deliver on promises to ensure accountability and accused the Rajapakse regime of becoming "increasingly authoritarian".
Sri Lanka's latest criticism of the UN official, set out in a 23-page statement, accused her of having a "preconceived, politicised and prejudicial agenda which she has relentlessly pursued with regard to Sri Lanka".
Pillay is South African of Tamil origin.
In a UN document leaked 10 days ago but published officially on Monday, Pillay asked the UNHRC to set up an independent probe and said Colombo had "consistently failed to establish the truth". Pillay's report noted fresh evidence of what took place during the final stages of the ethnic war that ended in May 2009 when an army onslaught crushed the Liberation Tigers of Tamil Eelam separatist guerrillas.
The UN has said up to 40,000 Tamil civilians may have been killed during the final months of fighting and blamed many of the atrocities on government forces, a charge Colombo vehemently denies.
A report released by the Public Interest Advocacy Centre in Australia this month said Sri Lankan soldiers committed the "vast majority" of crimes.
Rights group Amnesty International said Pillay's findings put pressure on the international community to support a probe at the UNHRC meeting. "It's utterly shameful that five years after Sri Lanka's armed conflict ended, the victims and family members have yet to see justice," Amnesty deputy Asia-Pacific director Polly Truscott said in a statement Tuesday. "Navi Pillay's latest report is another urgent and poignant reminder that an international investigation into alleged human rights violations and war crimes cannot wait."
Sri Lanka has previously said it needs more time to address issues of accountability and reconciliation after ending the 37-year-old conflict, which according to UN estimates claimed at least 100,000 lives.
One of Sri Lanka's main opposition parties, the communist People's Liberation Front or JVP, criticised Colombo's rights record but said it also opposed international action against the government. "The US and other Western nations have an imperialist agenda. That is why we oppose their action against Sri Lanka (at the UNHRC meet)," JVP leader Anura Kumara Dissanayake told reporters late on Monday. He urged Rajapakse to accept a South Africa-style truth and reconciliation commission to try to bring accountability.
Sri Lanka sent a top-level government delegation, including two ministers, to South Africa last week to study the commission there, but has yet to make a formal announcement on it.