An internal report into the United Nations’ handling of the final months of the bloody civil war in Sri Lanka has revealed that the organization failed in its mandate to protect civilians.

“Events in Sri Lanka mark a grave failure of the UN”, according to the ‘leaked’ report on Tuesday, says the BBC.

The draft criticized “sustained and institutionalized reluctance” among UN personnel in the country to stand up for the rights of Sri Lankans and condemned UN staff who “did not perceive the prevention of killing of civilians as their responsibility – and agency and department heads at the UNHQ were not instructing them otherwise”.

It also accused the UN of failing to make public that “a large majority” of civilian deaths were caused by government shelling, an assertion Colombo denied, AFP reports.

The brutal war between government forces and Tamil rebels claimed 400,000 civilian lives and displaced 290,000 over 27 years, according to UN estimates.

UN Secretary General Ban Ki-moon was determined to act on the report’s recommendations that the organization should “be able to meet a much higher standard in fulfilling its protection and humanitarian responsibilities” in the future, senior UN sources told the BBC.

The final report will be presented to Secretary General Ban Ki-moon before publication.