The United Nations has estimated those affected by the Myanmar cyclone at up to 2.5 million and called an urgent meeting of big donors and Asian states as the Myanmar junta continued to limit foreign aid.

The European Union's top aid official said the military government's restrictions were increasing the risk of starvation and disease.

UN humanitarian affairs chief John Holmes told reporters that there were now between 1.6-2.5 million people who were "severely affected" by Cyclone Nargis and urgently needed aid, up from a previous estimate of at least 1.5 million people.

Thai Prime Minister Samak Sundaravej said after a two-hour meeting in Yangon, where he urged his counterpart Thein Sein to ease visa rules for relief workers, that he was told Myanmar could "tackle the problem by themselves."

In New York, UN Secretary-General Ban Ki-moon, who has expressed frustration over the response by Myanmar's reclusive leaders, called a meeting of key donor states and Asian powers later on Wednesday to discuss "what kind of concrete measures we can do from now on."

"Even though the Myanmarese government has shown some sense of flexibility, at this time it is far, far too short," he said. "The magnitude of this situation requires much more mobilisation of resources and aid workers."

A Western diplomat said the meeting would be at 4:30 p.m. EDT (8:30 a.m. NZT) and that among those invited were the United States, Britain, France, Russia, China, India, Bangladesh, Australia and Japan.

TRICKLE OF AID

Nearly two weeks after the cyclone swept through the heavily populated Irrawaddy delta rice bowl, killing tens of thousands of people, foreign aid still amounts to little more than a trickle.

Myanmar, formerly called Burma, was once the world's biggest rice exporting country but more than 40 years of military rule have left it impoverished. The military junta has repeatedly crushed pro-democracy movements and tightly restricts visits by foreigners.

Samak told reporters in Bangkok that Myanmar's leaders had insisted that teams of foreign experts, who have been refused entry, were not needed.

"They are confident of dealing with the problem by themselves. There are no outbreaks of diseases, no starvation, no famine. They don't need experts, but are willing to get aid supplies from every country," Samak said.

Louis Michel, the top European Union aid official, disagreed.

"There is a risk of water pollution. There is a risk of starvation because the storages of rice have been destroyed," he told reporters in Bangkok before flying to Yangon to seek better access for international aid workers and relief efforts.

"We want to convince the authorities of our good faith. We are there for humanitarian reasons," he said, throwing cold water on suggestions foreign countries move unilaterally to bring in aid.

Even so, one EU member said on Wednesday it was time to act. "If need be, the international community must force the Burmese regime to let more help and relief workers in," Dutch Foreign Minister Maxime Verhagen said.

ACCESS IS "CRITICAL"

One group of Christian doctors has been treating children in churches, operating below the government's radar. "We have to try to do something," said one Asian doctor from the group, giving out medicine to children for diarrhea in a rickety wooden church in a village just north of Yangon.

World Food Program Executive Director Josette Sheeran said in Washington her organisation had so far reached 28,000 people. "A critical issue now is access. WFP has managed to reach more than 28,000 people with food aid so far, with 14 international and 214 national staff in-country," she said.

"Our flights are allowed to bring in some supplies, but far from enough - a massive effort is needed to save lives..." she said at a US Senate hearing on the global food crisis.

Holmes was asked if the United Nations might have to consider air drops to get food and other aid to cyclone victims who have not been helped and who are crowded into Buddhist monasteries and schools. He said it was not an ideal form of distributing aid but might become an option.

"It is something that could be contemplated," he said, adding that if barriers to aid workers were not lifted "one might have to look at it."

He also warned that epidemics of diseases like cholera, malaria and measles "can break out at anytime now."

Heavy rain and winds were forecast in the delta as a tropical depression moved in, but the UN weather agency discounted fears that a new cyclone was forming.

Myanmar state television raised its official toll to 38,491 dead, 1,403 injured and 27,838 missing on Wednesday.

The International Federation of the Red Cross estimated on the basis of reports from 22 organisations working in Myanmar that between 68,833 and 127,990 people had died.

ASIANS WELCOME, SAYS JUNTA

In a gesture to critics, Myanmar's rulers invited 160 personnel from Bangladesh, China, India and Thailand to assist in the sometimes chaotic relief efforts but that was a fraction of the number needed, experts said.

"It's just awful. People are in just desperate need, begging as vehicles go past," Gordon Bacon, an emergency coordinator for the International Rescue Committee, told Reuters from Yangon.

Some foreign aid workers who have reached Myanmar have been restricted to cobbling together assessment reports in Yangon for donors, based on what local staff tell them.

Experts say the relief effort is only delivering a tenth of the needed supplies. Heavy rains have slowed transportation of aid by land and added to the misery of tens of thousands of refugees packed into monasteries, schools and pagodas.

The operations in Myanmar are a shadow of the massive international relief operation begun just days after the 2004 Asian tsunami. The United States alone deployed thousands of its military and more than a dozen ships in the Indian Ocean.

So far the US military has made a total of eight aid flights into Yangon, an official said.

"We don't have confirmation of future flights yet but we are very optimistic," said Colonel Douglas Powell.

Three US naval ships were in international waters off Myanmar waiting for a go-ahead from Myanmar's generals.

Reuters