The government urged thousands of flag-waving supporters to use a May Day rally Sunday to protest the UN panel’s report, which concluded there were credible accusations that serious human rights violations — including possible war crimes and crimes against humanity — were committed by both the government and Tamil Tiger rebels in the last months of the 26-year war.

The protesters burned an effigy of UN Secretary-General Ban Ki-moon and depicted the three-member panel of UN experts in Tamil Tiger uniforms, implying they were partial to the defeated guerrillas. President Mahinda Rajapaksa told the crowd that the UN report will disrupt the country’s peace and reverse what has been achieved since the war ended in May 2009.

The comment was seen as a response to allegations in the report that government forces systematically blocked food and medicine, shelled civilians and hospitals, and deliberately undercounted the number of civilians trapped in the war zone.

The protesters carried national flags and placards as they marched in Colombo, saying the report was an international conspiracy to disturb peace and reconciliation since the war.

The report said the rebels forcibly recruited children to their fighting units, held civilians as human shields and shot civilians attempting to flee their grip.

According to UN documents, at least 7,000 people were killed in the last five months of the fighting. The world body says between 80,000 to 100,000 people may have been killed in the war.

The report also faulted UN agencies and international leaders, saying they failed to take steps to protect civilians.