COLOMBO: UN chief Ban Ki-moon came face-to-face Saturday with the despair of Sri Lanka's war-hit civilians as he toured the main refugee camp and flew over the devastated conflict zone.

On a 24-hour visit to the battle-scarred island nation, Ban went on foot through the sprawling Menik Farm camp, 250 kilometres (155 miles) north of Colombo, which is jammed with 200,000 civilians displaced by the fighting.

"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.

Ban's visit comes amid 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.

Aid agencies must be given "unhindered access" to the nearly 300,000 people in total displaced by the three-decade ethnic conflict, Ban said after his camp visit.

"The government is doing its utmost best," Ban told reporters after meeting President Mahinda Rajapakse in the central Sri Lankan temple town of Kandy.

But there is a "wide gap between what is needed and what can be done," he said, adding he had been assured international relief agencies would get more access to the so-called "welfare camps."

Tamil activists have likened the "welfare villages" to concentration camps because of the barbed wire surrounding them and the ominous presence of armed guards.

"The government lacks the resources," said Ban, who had described earlier the refugees as "badly in need of food, water and sanitation."

"With this in mind, the UN can help," he said. "The UN must be given immediate unhindered access to the camps, the overcrowding must end and there should be special programmes for pregnant mothers and children."

Ban, due to leave for Copenhagen late Saturday, stressed 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.

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.

Asked whether the armed security at the camp was there to stop people leaving, Ban replied: "I don't think they are holding them back for any particular purpose.

"They're trying to resettle them, to reintegrate them," he said. "That is the Sri Lanka government's commitment."

Ban said Foreign Minister Rohitha Bogollagama had promised him civilians would be resettled by the end of the year.

"It is time for Sri Lankans to heal the wounds and unite," Ban said.

Before meeting the UN chief, 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 percent of the 20 million population of the Sinhalese-majority island but have long complained of discrimination and restriction of movement.