COLOMBO: Sri Lankan protesters led by a cabinet minister rallied outside the UN office in Colombo on Wednesday, a day after laying siege to the building and trapping staff inside for several hours.

The United Nations expressed its anger at the protesters, who said they were campaigning against a UN panel set up to probe allegations of rights abuses during the Sri Lankan civil war that ended last year.

Demonstrators did not block the entrance of the UN office on Wednesday, though it was unclear whether staff had been ordered to stay away from work for the day.

"We will keep up the action until the UN panel is withdrawn," said Housing Minister Wimal Weerawansa, who has been leading the protests.

UN employees in Colombo were held inside their compound for seven hours on Tuesday until police moved in to allow them to leave amid rowdy scenes.

In New York, the United Nations said it had "strong objections" to the protests.

"While respecting the right of citizens to demonstrate peacefully, preventing access to UN offices hinders the vital work being carried out," UN associate spokesman Farhan Haq said in a statement.

The United States said it also respected the right to protest but that it backed UN Secretary-General Ban Ki-moon`s move to set up the panel.

The Sri Lankan government issued a statement backing demonstrators` wish to continue protesting until the UN "revisits the matter of the panel".

Sri Lanka has refused to cooperate with the panel, which was named by Ban last month to advise on "accountability issues" during the war between government forces and the Tamil Tiger separatists.

The Tiger guerrillas were defeated in May 2009 after decades of conflict, and the United Nations has said that at least 7,000 ethnic Tamil civilians were killed in the first four months of last year.

Many diplomats see the panel, headed by Marzuki Darusman, a former Indonesian attorney general, as a precursor to a full-blown war crimes investigation.

BDST: 1247 HRS, July 7, 2010