Burma's military leaders were accused today of deliberately keeping the full plight of suffering cyclone survivors from aid agencies.
The United Nations said that severe restrictions by the junta mean they lack the most basic information, from the number of orphans to the extent of diseases and the number of refugee camps.
They also could not say whether all survivors are in camps, on the move or still living in destroyed villages in the hardest-hit Irrawaddy delta, an area the size of Austria.
"The risk increases with each passing day," a spokeswoman said, referring to the vulnerability of survivors to outbreaks of disease and other problems.
Even the death toll has not been confirmed.
"Everyone is still using range of figures because we don't have data yet. Access is making that difficult ... We simply don't have the information, and I can't say when we will have it," said Steve Marshall, a UN official who just came out of Burma.
John Holmes, UN under-secretary-general for humanitarian affairs, will go to Burma on Sunday to try to convince junta leaders to grant more access for UN relief workers and massively scale up aid efforts.
The government today announced the official death toll had soared to 78,000 with nearly 56,000 missing. For most of the past week the number of dead has remained around 28,000.
The Red Cross fears the toll may be as high as 128,000; the UN estimates more than 100,000 died.
In the absence of a clear picture, the UN estimates some 1.5 million to 2.5 million survivors are in desperate need of food, water, shelter and medical care. Aid groups have reached only 270,000 so far.
The World Health Organisation said it had recorded the first cases of cholera.
The junta insists Burma nationals and government agencies, including the military, can handle relief operations, particularly aid distribution.
"We still have obstacles to relief workers getting to the delta region, which doesn't help," the UN spokeswoman said. "We are concerned about the effects on the people. It is clear, from what everyone is saying, the aid effort is far from over."
The UN said the regime has issued 40 visas to its staff and another 46 to non-government agencies but has confined the personnel to the immediate Rangoon area.
UN official Mr Marshall, laid out the hurdles that aid agencies face.
He said the military has set up checkpoints on the two main roads to the delta to keep foreigners out of the disaster zone. Even local staff have to negotiate with the military to gain access to the camps.
"Things will still get done, but they will not be done as effectively, efficiently or as quickly, which means delays, which means increasing risk in terms of health, security and in terms of longer-term rehabilitation and getting back to a normal lifestyle," he said.
Charities said figures from the worst-affected villages showed as many as 90% of the deaths were women, children and the elderly.
"Our figures in the camps show a lot of adults, but very few children and very few elderly," said Brian Agland, CARE International's country director in Burma.
"The worst-case scenario is that a lot of children may have drowned. In one village there were 500 survivors and they were all adults."
A Tearfund worker in Burma described one tragedy: "A man was stuck with his wife and child in the rapidly flowing water after the cyclone hit, clinging on for their lives.
"They were in the water for such a long time that he could no longer hold on to both of them. The mother pleaded for him to save the child. Finally, the father took the child and let go of the mother's hand and she disappeared into the giant water flow. When he looked at his child, he found that the child was already dead."
The UK's Disaster Emergency Committee said the women, children and elderly who do survive need extra support as they suffer the most.
"Women and children, unable to run as fast or swim as hard as men, are swept away by the flood waters. Elderly people who are incapable of moving as quickly die as they are trapped in their homes," it said.