The United States delivered its first relief supplies to Myanmar on Monday, as the U.N. urged the reclusive nation to open its doors to foreign experts who can help up to 2 million cyclone victims facing disease and starvation. The unarmed military C-130 cargo plane, packed with 28,000 pounds of supplies, flew out of the Thai air force base of Utapao and landed in Yangon, capping prolonged negotiations to persuade Myanmar's military government to accept U.S. help. Several Myanmar Cabinet ministers, military officers and the top U.S. diplomat in Myanmar, Shari Villarosa, greeted the plane.

Government spokesman Ye Htut said the aid, which was transferred to Myanmar army trucks, would be ferried by air force helicopters to the worst-hit Irrawaddy delta later Monday. Two more U.S. air shipments were scheduled to land Tuesday.

The official death toll from the May 3 Cyclone Nargis is 28,458 with another 33,416 still missing. But the U.N. Assistant Secretary-General Catherine Bragg and others have said the death toll could reach 100,000 or higher.

Though international assistance has started trickling in, the authoritarian government has barred most foreign experts who are experienced in managing humanitarian crises.

Richard Horsey, a spokesman for U.N. humanitarian operations, in Bangkok, Thailand, said clean drinking water, shelter, medical support and food were sorely lacking.

"The authorities of the country need to open up to an international relief effort. There aren't enough boats, trucks, helicopters in the country to run the relief effort of the scale we need," he said. "It's urgent that the authorities do open themselves up."

The junta has made a huge concession in letting the U.S. - the fiercest critic of its human rights record - bring in relief.

The U.S. plane carried mosquito nets, blankets and water in an operation dubbed "Joint Task Force Caring Response."

Also on the plane was Adm. Timothy J. Keating, the commander of the U.S. military in the Pacific, who will try to personally negotiate with the junta for a larger U.S. role in providing relief.

U.S. Marine spokesman Lt. Col. Douglas Powell said there are 11,000 service members and four ships in the region for an annual military exercise, Cobra Gold, that could be harnessed to help the mercy mission.

Three U.S. Navy ships in the Bay of Bengal were sailing closer to Myanmar on Monday, ready to aid cyclone victims if they are given permission, Vice Adm. Doug Crowder told reporters in Jakarta, Indonesia.

In Irrawaddy delta, people were surviving in miserable conditions - hundreds cramped in monasteries with little access to food. Others camped in the open, drinking dirty water contaminated by human feces or dead bodies and animal carcasses.

"The lives of thousands of cyclone survivors are at extreme risk," aid group World Vision said. "Displaced people are living in appalling conditions in makeshift shelters and camps where overcrowding and unsanitary conditions are prevalent."

Children - many of them orphans - are suffering from fever, diarrhea and respiratory infections, it said.

Heavy rains were forecast this week, which would further hinder aid delivery, even though it could be the only source of drinking water.

Thai Prime Minister Samak Sundaravej sent a letter to his Myanmar counterpart Monday, urging the junta to issue more visas. But the junta replied that visas for foreigners would be considered on a case-by-case basis, Thai government spokesman Wichianchote Sukchotrate said.

Samak's letter was carried by his personal envoy, Lt. Gen. Niphat Thonglek, who traveled to Myanmar on the U.S. plane, Wichianchote said. He said Myanmar informed Niphat that it will open the Thilawa port in Yangon to receive international relief supplies.

Still, the reclusive junta insists it will handle the aid distribution itself, through its feared military, which has ruled the country with an iron fist since 1962.

Many people have complained that they are getting rotting rice and that soldiers are keeping the best food for themselves.

"The government is very controlling," said U Patanyale, the abbot of a monastery in Kyi Bui Khaw village.

"Those who want to give directly to the victims get into trouble. They have to give to the government or do it secretly. They follow international aid trucks everywhere. They don't want others to take credit. That's the Myanmar government," he said.