UN chief Ban Ki-moon has come face-to-face with the despair of Sri Lanka's war-hit civilians during a tour of a key refugee camp while also flying over the devastated conflict zone.

sri lanka war against LTTE tamil tigers On a 24-hour visit to the battle-scarred island nation yesterday, Ban went on foot through the sprawling Menik Farm camp, 250 km north of Colombo, which is jammed with 200,000 civilians displaced by the fighting.

Ban described the conditions at the holding facility as overcrowded and said the civilians were "badly in need of food, water and sanitation."

"I'm very moved after what I have seen. I've seen so many wounded," the secretary-general said after spending 20 minutes walking through the camp, a sea of makeshift corrugated iron shacks and tents.

Sri Lanka had said they will allow UN aid workers access to the civilians who remain in the camps following the defeat of the Tamil Tigers, but only once rebels hiding among the refugees had been weeded out.

News of the Sri Lankan government announcement comes after Ban called for his staff to be given "unhindered access" to those displaced in the decades-long war, which ended a week ago.

Ban seeks full access into camps for relief agencies

There are widespread concerns that the government is preventing full humanitarian assistance from getting through to those in the camps after Colombo announced on Monday the Tamil Tiger rebels had been defeated.

sri lanka military operation against tamil tiger 150509 02 Tamil activists have likened the "welfare villages" to concentration camps because of the barbed wire surrounding them and the ominous presence of armed guards.

Ban stressed that other relief agencies, including the International Committee of the Red Cross, should also have "freedom of movement" in the camps.

The UN chief also flew by helicopter over the devastated war zone in northeastern Mullaittivu area where the final battles were fought by the rebels, who were seeking a separate state.

Seen from the air, the conflict zone was a desolate, cratered area with burnt-out vehicles and charred buildings along with an abandoned tent city.

There was virtually no sign of any people in the zone, off-limits to journalists and almost all aid agencies as the war reached its bloody conclusion.

sri lanka declare victory over tamil tigers war 190509 01 During his camp tour, Ban stopped at a clinic where he saw around 100 elderly patients, some with gaping wounds, who had been caught up in the conflict, which the UN says claimed 100,000 lives.

One 32-year-old man, who identified himself as Arunttavarasa, said through an interpreter that his mother "was killed by (army) shelling".

Both sides have been accused of rights violations, with campaign groups alleging indiscriminate army shelling and condemning the Tigers for using civilians as human shields.

Before meeting the UN chief, Sri Lanka's President Rajapakse told a religious gathering he would work for national reconciliation.

"We have a bigger responsibility now to rebuild our fractured nation," the president said.

Tamils make up 12.6 per cent of the 20 million population of the Sinhalese-majority island but have long complained of discrimination and restriction of movement.

- AFP