A U.S. plane ferried relief to Burma, renamed Myanmar by the ruling military junta, for the first time Monday, but with 2 million cyclone victims facing disease and starvation, a radical proposal was gaining ground: Airdropping aid without the junta's approval.

Even as the death toll from Cyclone Nargis climbed to 31,938, the country's military rulers continued to bar almost all foreign experts experienced in managing humanitarian crises, saying they would handle relief efforts on their own.

With hundreds of thousands of homes destroyed in the disaster zone, refugees packed into Buddhist monasteries. Others camped in the open, drinking dirty water contaminated by dead bodies and animal carcasses. Medicine and food were sorely lacking — even as supplies bottled up at the main international airport.

"The sands of time are running out," said Britain's opposition Conservative party leader David Cameron, suggesting aid should be airdropped into Burma if the junta does not provide access soon.

"In the end what matters is getting aid through to people and feeding them and stopping them from dying," he told BBC Radio.

Burma's hermetic rulers made a huge concession Monday in letting the United States — the fiercest critic of its human rights record — bring in relief following prolonged negotiations.

The U.S. military C-130 cargo plane filled with 14 tons of mosquito nets, blankets and water was unloaded in Rangoon, the country's largest city, providing what officials said was enough to help some 30,000 victims of the May 3 disaster.

It was immediately transferred to Burmese army trucks and would be ferried by air force helicopters to the worst-hit Irrawaddy delta, government spokesman Ye Htut told reporters.

U.S. military officials said they hoped it would be the start of a steady flow of aid, with two more flights planned for Tuesday.

"We hope they will allow us to do more in the future," said Lt. Col. Douglas Powell, the U.S. Marines spokesman for the operation. "It's really just up to what the Burmese will allow us to do."

The U.S. ambassador to Thailand, Eric John, was more direct.

"It is important that we, and the international community, be allowed to help," he said. "Let them in. Let them save lives."

Burma reported the official death toll from Cyclone Nargis had risen by nearly 3,500 to 31,938. Nearly 30,000 others remain missing, and the United Nations and others have said the death toll could reach 100,000 or higher.

U.N. Secretary-General Ban Ki-moon chided the junta for its "unacceptably slow response" to helping between 1.5 million and 2 million people left homeless or in dire need.

"There is no aid. We haven't seen anyone from the government," said U Pinyatale, the 45-year-old abbot of a monastery sharing almost depleted rice stocks and precious rainwater with some 100 homeless villagers huddled within its battered compound.

The first British aid flight packed with the plastic sheets, which will provide shelter to more than 9,000 families, was also on its way to Rangoon, which was pounded by heavy rain on Monday.

More downpours were expected later this week, which would further hinder aid delivery, even though it could be the only source of drinking water.

"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.

Also Monday, two planes carrying 56 tons of medical and other aid from Europe-based humanitarian groups arrived in Rangoon.

Three more planes were en route, said one of the organizations, Medecins Sans Frontieres, though it protested "growing restrictions" by the military on the movement of aid within the country.

Burma's government has less than 40 helicopters, most of them small or old. It also has only about 15 transport planes, primarily small jets unable to carry hundreds of tons of supplies.

"The authorities of the country need to open up to an international relief effort," said Richard Horsey, a spokesman for U.N. humanitarian operations, in Bangkok, Thailand.

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

With the arrival of the first U.S. military plane in Rangoon, the question remained just how much more help the Americans would be allowed to provide.

On board 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 Burma on Monday, ready to aid cyclone victims if they are given permission, Vice Adm. Doug Crowder told reporters in Jakarta, Indonesia.

Calls mounted, meanwhile, for airdropping aid into the country, with or without the junta's approval — a prospect that, at present, seemed unlikely.

"Well, I don't think anybody now at this stage is seriously considering airdropping," said Terje Skavdal, head of the U.N. Office for the Coordination of Humanitarian Affairs. "I think the issue now is trying to build the better possible relationship with the government to get the best possible access."

U.S. Defense Secretary Robert Gates also said last week he could not imagine dropping aid without the consent of authorities, and the office of British Prime Minister Gordon Brown seemed to agree.

But French Foreign Minister Bernard Kouchner said last week that airdrops could be allowed under the United Nations' "responsibility to protect" mandate, which applies to civilians. He said then discussions were under way at the U.N. on a possible resolution imposing the passage of aid on Burma's government.

Many survivors complain they are getting rotting rice and 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.