Burma is struggling to cope with the devastation wrought by Tropical Cyclone Nargis, which hit the country on Saturday.
State media say at least 22,000 people were killed and another 41,000 are missing.
Almost all of the deaths occurred in the Irrawaddy river delta region, where more were killed by the tidal wave than the cyclone itself. Large swathes of the southern coastal area are still under water.
Hundreds of thousands of people across the affected areas are said to lack shelter and clean drinking water.
The cyclone also caused massive damage in Burma's former capital, Rangoon, felling trees and cutting power supplies.
Burma's military rulers have declared five regions disaster zones, and signalled that the country will accept external help.
Aid agencies are pushing for immediate access to the affected areas. Aid shipments from neighbouring Thailand are due to arrive shortly.
A BBC correspondent in Burma says that more than half a million people in the Irrawaddy delta are thought to need emergency assistance.
The Red Cross, which has 18,000 local volunteers in Burma, says the country faces an enormous catastrophe.
The Red Cross says it is particularly worried about food shortages.