The plea came in an oral update to the HRC in Geneva by Navi Pillay, the U.N. high commissioner for human rights, following her visit last month to the Indian Ocean island nation. The Sri Lankan government of President Mahinda Rajapaksa has been accused of being authoritarian.
Pillay's update to the UNHRC was read by her deputy.
"The High Commissioner is convinced that the continued attention of the Human Rights Council to the human rights situation in Sri Lanka remains critically important and will be making recommendations in March on appropriate ways it could continue that engagement," the update said.
The Rajapaksa government has come under pressure since the Sri Lankan military crushed the 25-year Tamil separatist rebellion four years ago. Thousands of civilians reportedly died in the military action, raising calls from rights groups for an investigation into alleged violations.
Pillay said during her visit to Sri Lanka she observed "the impressive achievements" of the government in resettlement, reconstruction and rehabilitation of those displaced during the 2009 military action and noted the government has invited the Special Rapporteur make an assessment.
However, she said four years since the end of the war, the military presence in the north remains considerable and communities she met reported that "there is a high level of surveillance of returnees, rehabilitees and detainees who have been released."
There were also reports of "compulsory acquisition of private land" in the Tamil areas in the north.
Pillay said she was "particularly alarmed at the recent surge in incitement of hatred and violence against religious minorities," and the lack of swift action against the perpetrators.
Pillay said she also heard complaints about the continuing high levels of harassment and intimidation of human rights defenders, lawyers and journalists. She also observed great disquiet among many commentators and stakeholders "about the degree to which the rule of law and democratic institutions in Sri Lanka are being undermined and eroded."
She said she detected no new or comprehensive effort to independently or credibly investigate the allegations which have been of concern to the Human Rights Council.
She urged the government to engage in the next six months "in a credible national inquiry with tangible results" into reported rights violations. Failing that, Pillay said she believes "the international community will have a duty to establish its own inquiry mechanisms."
The New York Times reported Sri Lankan Ambassador to the United Nations in Geneva Ravinatha Aryasinha rejected Pillay's observations as "not the result of an objective assessment."