Burma's state media said last weekend's cyclone killed some 10,000 people in one town alone, raising fears of a big rise in the overall death toll today.
The 10,000 perished over the weekend in the town of Bogalay in the low-lying Irrawaddy delta, the hardest hit area when Cyclone Nargis struck Saturday, state television said.
The new tally marked a significant increase over state media reports yesterday.
The country's ruling junta, which has spurned the international community for decades, urgently appealed for foreign aid at a meeting yesterday among Foreign Minister Nyan Win and diplomats in Rangoon, and foreign governments were poised today to rush aid to the Southeast Asian nation.
The appeal came less than a week ahead of a crucial referendum on a military-backed constitution that the ruling junta hoped would go smoothly in its favour, despite opposition from the country's feisty pro-democracy movement.
However, the disaster could stir the already tense political situation, several analysts said.
A military transport plane was scheduled to land in Rangoon later today with emergency aid from Thailand, while a number of other countries and organisations said they were prepared to follow.
The United States, which has slapped economic sanctions on the country, said it likewise stood ready, but that a US disaster team must be invited into the country.
The storm has left hundreds of thousands of people homeless and without clean drinking water, said Richard Horsey, a spokesman in Bangkok, Thailand for the United Nations Office for the Coordination of Humanitarian Affairs.
Relief Minister Major General Maung Maung Swe said at the meeting with diplomats that the referendum scheduled for Saturday could be postponed by "a few days" in the worst-affected areas, but state media indicated yesterday that the May 10 date was still set.
The diplomats said they were told Burma welcomed international aid, including urgently needed roofing materials, medicine, water purifying tablets and mosquito nets. The Thais were sending a shipment of nine tons of such supplies.
The appeal for assistance was unusual for Burma's ruling generals, who have long been suspicious of the international organisations and have closely controlled their activities.
The UN's Horsey said it appeared the United Nations had the green light to send in a team to assess the storm's damage as early as today.
The wife of the US president said her country was ready to pump aid into Burma for recovery efforts, but that the ruling junta must accept a US disaster response team in the country.
First Lady Laura Bush, who has been the administration's chief voice on human rights and political conditions in Burma, faulted the junta for proceeding with the constitutional referendum, which she described as a sham, and criticised government leaders for not sufficiently warning citizens about the storm.
"We know already that they are very inept," she said.
There was little sign of official efforts to repair the damage in Rangoon, but the worst-hit areas were in the countryside, now inaccessible by road because of storm damage.
"The combination of the cyclone and the referendum within a few days of each other makes an angry population angrier and vulnerable and makes the political situation more volatile" than it has been since last year's massive pro-democracy demonstrations, said Monique Skidmore, a Burma expert at Australian National University.
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.
The government had apparently taken few efforts to prepare for the storm, which came bearing down on the country from the Bay of Bengal late Friday.
Weather warnings broadcast on television would have been largely useless for the worst-hit rural areas where electricity supply is spotty and television a rarity.
"The government misled people," said Thin Thin, a grocery story owner in Rangoon. "They could have warned us about the severity of the coming cyclone so we could be better prepared."
Rangoon, where officials said 59 people died, was without electricity except where gas-fed generators were available and residents lined up to buy candles at double the usual price.
Most homes were without water, forcing families to stand in long lines for drinking water and bathe in the city's lakes.
Most telephone landlines appeared to be restored by late yesterday, but mobile phones and internet connections were down.
Some in Rangoon complained that the 400,000-strong military was only clearing streets where the ruling elite resided but leaving residents, including Buddhist monks, to cope on their own in most other areas.
Burma has been under military rule since 1962. Its government has been widely criticised for suppression of pro-democracy parties such as the one led by Nobel Peace Prize laureate Aung San Suu Kyi, who has been under house arrest for almost 12 of the past 18 years.