YANGON, MYANMAR - The Red Cross estimated Wednesday that the cyclone death toll in Myanmar could be as high as 128,000 -- a much higher figure than the government tally.

The U.N. warned that a second wave of deaths will follow unless the military regime quickly lets in more aid.

The grim forecast came as heavy rains drenched the devastated Irrawaddy River delta, disrupting aid operations already struggling to reach up to 2.5 million people in urgent need of food, water and shelter.

"Another couple of days exposed to those conditions can only lead to worsening health conditions and compound the stress people are living in," said Shantha Bloemen, a spokeswoman for UNICEF.

A tropical depression in the Bay of Bengal added new worries, but late in the day forecasters said it was weakening and unlikely to grow into a cyclone.

Myanmar's government issued a revised casualty toll Wednesday night, saying 38,491 were known dead and 27,838 were missing.

The International Federation of Red Cross and Red Crescent Societies, however, said its estimate put the number of dead between 68,833 and 127,990.

The Geneva-based body said the range came from a compilation based on other estimates from 22 different organizations, including the Myanmar Red Cross Society, and on media reports.

Even though the figures seemed precise, spokesman Matthew Cochrane said they were not based on body counts but were only rough estimates designed to give Red Cross donors and partner organizations an idea of the numbers being discussed within the aid community.

U.N. officials have said there could be more than 100,000 dead.

But the junta still refused to accept help from foreign aid experts, who have vast experience in handling humanitarian crises.

It insisted Myanmar can handle the disaster on its own -- a stance that appeared to stem not from the isolationist regime's ability but from its deep suspicion of most foreigners, who have frequently criticized its human rights abuses and crackdowns on democracy activists.

"The government has a responsibility to assist their people in the event of a natural disaster," said Amanda Pitt of the U.N. Office for Humanitarian Affairs.