LONDON (AFP) ― The United Nations failed in its mandate to protect civilians in the final months of Sri Lanka’s civil war, according to a draft of a damning internal U.N. report seen by the BBC on Tuesday.

“Events in Sri Lanka mark a grave failure of the U.N.,” the draft said, adding that the world body should “be able to meet a much higher standard in fulfilling its protection and humanitarian responsibilities.”

Sri Lankan forces finally crushed Tamil rebels in May 2009 following decades of brutal fighting. The conflict claimed up to 100,000 lives, according to U.N. estimates, and both sides are accused of war crimes.

The report blasts senior U.N. staff in the Sri Lankan capital Colombo who “did not perceive the prevention of killing of civilians as their responsibility ― and agency and department heads at UNHQ were not instructing them otherwise.”

It accuses the U.N. of failing to make public that “a large majority” of civilian deaths were caused by government shelling, a charge Colombo repeatedly denied.

At U.N. headquarters in New York, the report continues, “engagement with member states regarding Sri Lanka was heavily influenced by what it perceived member states wanted to hear, rather than by what member states needed to know if they were to respond.”

The internal panel also questioned the U.N.’s decision to pull out its staff from the Sri Lankan war zone in September 2008 after the government warned it could no longer guarantee their safety.

Benjamin Dix, who was part of the U.N. team that left, was against the pullout.

“I believe we should have gone further north, not evacuate south, and basically abandon the civilian population with no protection or witness,” Dix told the BBC.

“As a humanitarian worker, questions were running through my mind ‘what is this all about? Isn’t this what we signed up to do?’”

Senior U.N. sources told the BBC that U.N. Secretary General Ban Ki-moon was determined to act on the report’s recommendations in order to “learn lessons” from Sri Lanka and respond more effectively to new international crises such as the bloodshed in Syria.

The U.N. told the BBC that it did not comment on leaked reports and that it would publish the final version.