The cyclone death toll soared above 22,000 on Tuesday and more than 41,000 others were missing as foreign countries mobilized to rush in aid after the country's deadliest storm on record, state radio reported.
Up to 1 million people may be homeless after Cyclone Nargis hit the Southeast Asian nation, also known as Burma, early Saturday. Some villages have been almost totally eradicated and vast rice-growing areas are wiped out, the World Food Program said.
Images from state television showed large trees and electricity poles sprawled across roads and roofless houses ringed by large sheets of water in the Irrawaddy River delta region, which is regarded as Myanmar's rice bowl.
"From the reports we are getting, entire villages have been flattened and the final death toll may be huge," Mac Pieczowski, who heads the International Organization for Migration office in Yangon, said in a statement.
President Bush called on Myanmar's military junta to allow the United States to help with disaster assistance, saying the U.S. already has provided some assistance but wants to do more.
"We're prepared to move U.S. Navy assets to help find those who have lost their lives, to help find the missing, to help stabilize the situation. But in order to do so, the military junta must allow our disaster assessment teams into the country," he said.
Bush spoke at a ceremony where he signed legislation awarding the Congressional Gold Medal to Burmese democracy advocate Aung San
Myanmar's military regime has signaled it will welcome aid supplies for victims of a devastating cyclone, the U.N. said Tuesday, clearing the way for a major relief operation from international organizations.
But U.N. workers were still awaiting their visas to enter the country, said Elisabeth Byrs of the U.N. Office for the Coordination of Humanitarian Affairs.
"The government has shown a certain openness so far," Byrs said. "We hope that we will get the visas as soon as possible, in the coming hours. I think the authorities have understood the seriousness of the situation and that they will act accordingly."
The appeal for outside assistance was unusual for Myanmar's ruling generals, who have long been suspicious of international organizations and closely controlled their activities. Several agencies, including the International Red Cross and Doctors Without Borders, have limited their presence as a consequence.
Allowing any major influx of foreigners could carry risks for the military, injecting unwanted outside influence and giving the aid givers rather than the junta credit for a recovery.
However, keeping out international aid would focus blame squarely on the military should it fail to restore peoples' livelihoods.
Some aid agencies reported their assessment teams had reached some areas of the largely isolated region but said getting in supplies and large numbers of aid workers would be difficult.
Shari Villarosa, the top American diplomat in Yangon, told NBC's "Today" show that the cyclone had knocked huge trees in the
country's largest city.
"And it blew down a significant portion of them, some of these are 6, 8, 10 stories tall - huge trees, 6 feet, 5 feet in diameter. So they came down on roofs," she said.
The cyclone came only a week ahead of a key referendum on a constitution that Myanmar's military leaders hoped would go smoothly in its favor, despite opposition from the country's feisty pro-democracy movement. However, the disaster could stir the already tense political situation.
State radio also said that Saturday's vote would be delayed until May 24 in 40 of 45 townships in the Yangon area and seven in the Irrawaddy delta, which took the brunt of the weekend storm. It indicated that the balloting would proceed in other areas as scheduled.
The decision drew swift criticism from dissidents and human rights groups who question the credibility of the vote and urged the junta to focus on disaster victims.
Myanmar's generals have hailed the referendum as an important step forward in their "roadmap to democracy." It offers the first chance for voters to cast ballots since 1990, and the probability is high they will approve the constitution - a legal framework the country has lacked for two decades.
But critics, including the United Nations, the United States and human rights groups, question whether it will lead to democracy.
Myanmar has been under military rule since 1962. Its government has been widely criticized for suppression of pro-democracy parties such as the one led by Suu Kyi, a Nobel Peace Prize laureate who has been under house arrest for almost 12 of the past 18 years.
At least 31 people were killed and thousands more were detained when the military cracked down on peaceful protests in September led by Buddhist monks and democracy advocates.
Washington has long been one of the ruling junta's sharpest critics for its poor human rights record and failure to hand over power to a democratically elected government.