Updated

An independent investigatory panel has accused Sri Lankan security forces of arbitrary killings, torture and rape in the final months of the country's 27-year civil war.

A report by the Australia-based Public Interest Advocacy Center released Wednesday also accuses Sri Lanka's government of systematically trying to destroy evidence of mass civilian deaths. The report calls for an international investigation into allegations of war crimes.

Sri Lanka's government has refused demands by the United Nations for an independent investigation into alleged wartime atrocities committed by rebels and soldiers. The U.N. says at least 40,000 ethnic Tamil civilians may have been killed in just the final months of the fighting in 2009.

The report was produced by a five-member panel of experts who examined testimony from witnesses, documentary evidence and other reports.