Speaking after the first U.S. military aid flight to Burma on Monday, U.S. President George W. Bush condemned the junta for failing to act more quickly to accept international help, saying "either they are isolated or callous."
"It's been days and no telling how many people have lost their lives as a result of the slow response," he said in a radio interview with CBS News.
The C-130 military transport plane flew in from an air base in neighbouring Thailand carrying water, mosquito nets and blankets, but U.S. officials involved in the relief effort were not allowed beyond Yangon airport.
A stream of other aid flights have already landed in Yangon, but only a fraction of the help is getting to where it is needed.
The World Food Programme said it was able to deliver less than 20 percent of the 375 tonnes of food a day it wanted to move into the flooded delta.
At the United Nations in New York, Secretary-General Ban Ki-moon delivered his most critical comments so far.
"I want to register my deep concern - and immense frustration - at the unacceptably slow response to this grave humanitarian crisis," he told reporters.
The United Nations said its top representative in Burma had flown to Naypyidaw, the generals' new capital, on Monday to hand over a list of 60 critical U.N. and relief agency staff. More than 30 visas had since been promised, the U.N. said.
In its latest assessment, its humanitarian agency said between 1.2 million and 1.9 million people were struggling to survive and the number of dead ranged from 60,000 to 102,000.
Burma state television raised its official toll to 31,938 dead and 29,770 missing on Monday. Most of the casualties were killed by the 12-foot (3.5 metre) wall of water that hit the delta, with the cyclone's 190 kph (120 mph) winds.
The cyclone raged through an area that is home to nearly half of the country's 53 million people, as well as its main rice-growing region. About 5,000 sq km (1,930 sq miles) of land remain under water.
France was sending a warship carrying 1,500 tonnes of rice which was expected near Burma later this week. Paris says it wants to distribute the food directly itself, but will not do so without authorisation.
The United States will also have three ships near Burma this week, and Britain was sending a navy ship to the region to help humanitarian operations.
