The United Nation’s top human rights body on Thursday adopted a US-led resolution asking Sri Lanka to conduct an independent and thorough investigation into alleged war crimes carried out during the final phase of the country’s civil war.

By a 25-13 vote, the 47-nation UN Human Rights Council passed the resolution highly critical of Sri Lanka’s slow progress in investigating alleged human rights violations committed by the government and separatist Tamil rebels in the final months leading to the end of the brutal 26-year war in 2009.

The resolution followed a UN report alleging the government may be to blame for tens of thousands of civilian deaths during the military campaign to defeat the rebels, reports The Associated Press.

The resolution calls upon the Sri Lanka government “to conduct an independent and credible investigation” into allegations of human rights, such as summary executions, kidnappings and other abuses.

Sri Lanka’s representative at the council denounced the resolution as “intrusive” to the country’s domestic affairs and could endanger an ongoing reconciliation process.

A Sri Lankan commission report in December 2011 cleared the government forces of alleged human rights abuses.

India backed the UN vote after the DMK, an Indian Tamil party, pulled out of the country’s ruling coalition in protest at New Delhi’s soft stance against the Sri Lankan government, Financial Times reports.