UN spokesman Farhan Haq

President called for this year's May Day rally to be turned into a "show of strength" against international calls for a war crimes investigation.

"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 told the BBC Sandeshaya on Monday.

Sources are unsubstantiated

Speaking to the media during a visit to Bangladesh, External Affairs Minister G.L. Pieris said that the government find the report biased. "Sources are unsubstantiated", said the minister.

"We will be making more detailed observations" the minister stated.

The report compiled by the UN advisory committee appointed by the General Secretary to look into alleged war crimes committed during the fight against Tamil Tiger rebels, will be officially released by the United Nations this week, Farhan Haq told BBC.

Handed over to government

The report was handed over to the government of Sri Lanka prior to its release to the public.

"Countries must deal with their own problems according to their own culture, value systems and history", External Affairs minister G. L. Pieris told the media in Dhaka on Tuesday.

Details of the report were leaked to a Sri Lankan newspaper and published at the weekend.

Credibal allegations of war crimes

It says there were "credible" allegations that Sri Lankan government forces and the rebels committed war crimes and crimes against humanity in the final stages of the war.

I do not know who leaked the report. It did leak to a Sri Lankan newspaper and it did leak shortly after we gave the report to the government of Sri Lanka Farhan Haq

Answering questions during a UN press briefing, Farhan Haq said the details of the report released by The Island newspaper in Sri Lanka, were accurate but an "incomplete" account.

"I do not know who leaked the report. It did leak to a Sri Lankan newspaper and it did leak shortly after we gave the report to the government of Sri Lanka but I do not know definitively who it was who turned this over," Haq said.

"Whenever we share a communication with a member state there is an understanding that it will not be leaked," he added.