"We have made it very, very clear to the government of Sri Lanka that we take it very seriously that they ensure the security and safety of UN staff in Sri Lanka," UN deputy spokesman Farhan Haq said.
"We have underscored that again and we want to make sure that regardless of what their positions are on the report that they abide by their obligations to the security of our staff," Haq told a press briefing.
The report by UN experts into alleged war crimes committed during the fight against Tamil Tiger rebels, which ended in 2009, is to be officially released by the United Nations this week.
Details of the report were leaked to a Sri Lankan newspaper and published at the weekend. It says there were "credible" allegations that Sri Lanka committed war crimes and crimes against humanity in its final 2009 offensive