The UN called on Wednesday on Sri Lanka to investigate an incident in which soldiers fired on war refugees held in a cramped displacement camp, wounding at least two people, including a child.
Human rights activists have repeatedly complained about conditions in the northern camps, where nearly 300,000 Tamil civilians forced from their homes by civil war have been detained for months.
The incident appeared to highlight the growing frustration of the civilians in the camps.
The shooting erupted on Saturday, when camp inmates attacked a group of soldiers in anger over being prevented from moving between zones of the heavily guarded Manik Farm camp, the UN refugee agency said in a statement.
"Security personnel then reportedly opened fire to disperse the mob. Several people are said to have been injured, including a child who was hit by a stray bullet and is now paralysed," the statement said.
The agency called on the government to ensure the safety of the war refugees and undertake a "swift investigation."
Military spokesman Brig Udaya Nanayakkara said earlier that the soldiers only fired in self defence to disperse the violent crowd.
The shooting was the worst reported incident of violence since the government opened the camps earlier this year to detain those fleeing the final stages of the fighting between the military and the Tamil Tiger rebels.