Sri Lanka's military says there cannot be open access to camps where displaced Tamils are being held because of concern rebel cadres are among the nearly 300,000 displaced civilians there.
Access has eased for aid agencies to Sri Lanka's largest camp for Tamils displaced by the recently-ended civil war.
United Nations officials say, since the visit of the secretary-general, Saturday, vehicles carrying humanitarian agency worker can again enter the Manik Farm camp. But the vehicles cannot travel in convoys nor display their agency flags.
Manik Farm is the largest such camp, housing more than 200,000 of the internally displaced people.
Sri Lankan Army Brigadier Udaya Nanayakkara tells VOA News unrestricted access and movement cannot be permitted because of concerns about lingering elements of the defeated Liberation Tigers of Tamil Eelam.
"There can be LTTE cadres, sleeping cadres, in these camps. We will have an eye on them. And, that's the main reason for us to have the access control and all these procedures being adopted to safeguard the civilians kept in these welfare camps," he said.
Critics assert the sprawling 570-hectare facility erected on scrubland is a government-run detention center, ringed by barbed wire and under guard by the Sri Lankan Army and police.
Residents displaced by the war interviewed by VOA, in recent days, complain they are not allowed to leave the facility and that medical care, sanitation and hygiene are inadequate.
The island nation's quarter-century civil war came to an end this month, when the military defeated the Tamil Tigers. The rebels had once controlled one-third of the country, in their quest to establish a separate ethnic homeland.
Sri Lankan Foreign Minister Rohita Bogollagama is hailing what his government calls its "resounding victory" at Wednesday's meeting of the United Nations Human Rights Council. The council rejected language that would have allowed an independent investigation into violations of human rights and humanitarian law by the Sri Lankan forces.
Supporters of the investigation argued that both the Sri Lankan military and the rebels appear to have committed such abuses.
The international organization Human Rights Watch says the U.N. council approved a "deeply flawed resolution" that ignored urgent needs for the displaced Tamils and "wasted an important chance to promote human rights." The non-governmental organization singles out Brazil, Cuba, India and Pakistan for leading the effort to prevent the passage of a stronger resolution.