"Months after the conflict ended, our main concerns haven't changed. People are still not given free access to leave these camps on their own free will," UN humanitarian chief John Holmes told AFP after a visit to the camps.
Holmes, who ended a three-day visit on Thursday, said some 130,000 men, women and children remained inside the tightly-guarded camps.
More needs to be done to improve their living conditions, the UN under secretary general for humanitarian affairs added.
"We are very much encouraged by the government's progress to resettle people. There were about 288,000 people in May (when the conflict ended) and now its much less," Holmes said.
He asked the government to allow those returning to their villages a greater say in their resettlement.
"People need to be consulted as much as possible on where they are going, the status of their homes, their livelihoods."
"But I must say that those who have been allowed to return are quite relieved to get out of the camps a