The secretary-general was the first major international figure to visit since President Mahinda Rajapaksa declared victory over the Tamil Tiger rebels on Monday, crushing their dream of a separate state for the Tamil minority.
Ban later flew by helicopter over the wasteland along the northeastern coast where the final battles raged. The earth was scorched and the area was pocked with craters. Cars and trucks were overturned and bunkers were dug outside tents clustered in the area.
Human rights groups and international officials accused the government of heavily shelling the area, densely populated with civilians, in the last weeks of the war. The government denied using heavy weapons.
Nearly 300,000 Tamil civilians were displaced in the final months of fighting and sent to dozens of government-run camps in the north.
The main camp, known as Manik Farm, holds a vast expanse of white tents neatly lined up in rows on dirt paths. Roads between the tents are crammed with people, and barbed wire fences encircle the area, keeping the tens of thousands of civilians from getting out. Soldiers are stationed across the camp.
Men and women were scooping water from a well and bathing awkwardly in the open air, trying to maintain some privacy.
Aid groups have appealed to the government to allow the displaced more freedom, but military officials say it is too dangerous to let them out because rebels could be hiding among the civilians.
Some of the camp residents held signs welcoming Ban on his 24-hour trip here.
Aid agencies have complained the government is restricting access to the camp, allowing in only essential supplies of food and water. Chicken pox and skin diseases are sweeping through the camp and hepatitis is a growing problem because of poor sanitation, the Oxfam aid agency said.
On board a U.N. peacekeeping plane on his way to Sri Lanka, Ban said his first priority was "unimpeded access" for U.N. agencies and humanitarian workers.
"I know that there are more than 300,000 displaced persons who are badly in need of humanitarian assistance
- food, water and sanitation," he said.
His second major goal, he said, is to seek the reunification of families and to help reintegrate a broken society. He also said he wants to help reconcile Sri Lanka and its people.
The Tamils, 18 percent of the population, claim systematic discrimination and harassment by the Sinhalese majority.
"Now that the long decades of conflict are over, it is time for Sri Lankans to heal the wounds and unite without regards to ethnic and religious identity," Ban said at the airport on his arrival.
