Myanmar's military junta believes at least 10,000 people died in a cyclone that ripped through the Irrawaddy delta, triggering a massive international aid response for the pariah state in southeast Asia.
"The basic message was that they believe the provisional death toll was about 10,000 with 3,000 missing," a Yangon-based diplomat said in Bangkok, summarising a briefing from Foreign Minister Nyan Win. "It's a very serious toll."
The scale of the disaster from Saturday's devastating cyclone drew a rare acceptance of outside help from the diplomatically isolated generals, who spurned such approaches in the aftermath of the 2004 Indian Ocean tsunami.
The secretive military, which has ruled the former Burma for 46 years, has moved even further into the shadows in the last six months due to the widespread outrage at its bloody crackdown on protests led by Buddhist monks in September.
The official toll on state media stands at 3,394 dead and 2,879 missing, although those figures only cover two of the five declared disaster zones, where UN officials say hundreds of thousands are without shelter or drinking water.
The casualty count has been rising quickly as authorities reach hard-hit islands and villages in the Irrawaddy delta, the former "rice bowl of Asia" which bore the brunt of Cyclone Nargis's 190 kilometres per hour winds.
After getting a "careful green light" from the government, the UN said it was pulling out all the stops to send in emergency aid such as food, clean water, blankets and plastic sheeting.
"The UN will begin preparing assistance now to be delivered and transported to Myanmar as quickly as possible," World Food Programme (WFP) spokesman Paul Risley said.
The US, which has imposed sanctions on the junta, said it had provided $250,000 in immediate assistance and a disaster response team was on standby.
"At this moment as I understand it the Burmese government has not given them permission to go into the country," State Department spokesman Tom Casey told reporters.
Two Indian naval ships loaded with food, tents, blankets, clothing and medicines would sail for Yangon soon, Indian's Ministry of External Affairs said.
The UN office in Yangon said there was an urgent need for plastic sheeting, water purification tablets, cooking equipment, mosquito nets, health kits and food.
It said the situation outside Yangon was "critical, with shelter and safe water being the principal immediate needs".
The junta leaders, bunkered in their remote new capital of Naypyidaw, 400 kilometres north of Yangon, said they would go ahead with a May 10 referendum on a new army-drafted constitution that critics say will entrench the military.
The last major storm to ravage Asia was Cyclone Sidr which killed 3,300 people in Bangladesh last November.
In the former capital Yangon, food and fuel prices soared and aid agencies scrambled to deliver emergency supplies and assess the damage in the five declared disaster zones, home to 24 million people.
Clean water was scarce. Most shops had sold out of candles and batteries and there was no word when power would be restored.
Long queues formed at the few open petrol stations. The price of petrol has doubled on the black market, while egg prices have tripled since Saturday.
"How many people are affected? We know that it's in the six figures," Richard Horsey, of the UN disaster response office, said after an emergency aid meeting in Bangkok yesterday before the state TV announcement.
"We know that it's several hundred thousand needing shelter and clean drinking water, but how many hundred thousand we just don't know."
In Yangon, many roofs were ripped off even sturdy buildings, suggesting damage would be severe in the shanty towns that lie on the outskirts of the city of five million people.
At the city's notorious Insein prison, soldiers and police killed 36 prisoners to quell a riot that started when inmates were herded into a large hall and started a fire to try to keep warm, a Thailand-based human rights group said.
State television showed military and police units on rescue and cleanup operations in Yangon, but residents complained the junta's response was weak.
"Where are the soldiers and police? They were very quick and aggressive when there were protests in the streets last year," a retired government worker said.