Burma's military regime allowed the U.N. humanitarian chief into the devastated Irrawaddy delta for a brief tour Monday, a U.N. official said.

But the United Nations said its foreign staff were still barred from the delta and described conditions there as "terrible," with hundreds of thousands of cyclone victims suffering from hunger, disease and lack of shelter.

John Holmes, the U.N. undersecretary-general for humanitarian affairs, flew by helicopter to the delta before returning to Burma's largest city, Rangoon, for a working lunch with international aid agencies, said a U.N. official who spoke on condition of anonymity because he was not authorized to speak with the media.

Others, including U.N. Secretary-General Ban Ki-moon, will also be allowed into the disaster zone this week in an apparent effort to deflect criticism that the government is not managing the relief operations properly.

An Asian diplomat said Burma, renamed Myanmar by the ruling military junta, has invited at least three representatives of several countries to tour the delta Friday. He spoke on condition of anonymity because the news has not been made public.

Ban is to travel to the delta after his scheduled arrival in the country Wednesday, U.N. spokeswoman Michele Montas said in New York.

Earlier, junta leader Senior Gen. Than Shwe had refused to take telephone calls from Ban and had not responded to two letters from him, Montas said. Holmes, who arrived in Yangon on Sunday, was to deliver a third letter about how the U.N. can assist the government's immediate and long-term relief effort.

"With the visit of John Holmes and the U.N. secretary-general on Wednesday I hope the government will really accept all the international support that is necessary," Ramesh Shrestha, head of the U.N. Children's Fund in Burma, told The Associated Press.

"At this time of crisis, everyone needs to set aside their ideological issues. We need to resolve this right now," he said.

Amanda Pitt, a U.N. spokeswoman in Bangkok, said the world body was seeing "some progress in terms of pipelines starting to come through" but that the aid operation was still unsatisfactory.

"Clearly we're still not satisfied, which is why we keep saying we need to upscale the response. We're not satisfied with it, nobody is. We can see the situation is terrible," she said.

In Singapore, Southeast Asian nations — criticized for being too lenient with the junta — held an emergency meeting of their foreign ministers to try to make Burma accept more international aid.

Critics have accused the Association of Southeast Asian Nations, a 10-member bloc that includes Burma, of doing little so far to persuade the ruling generals to rapidly let in outside help, especially disaster experts.

European Union nations have warned the junta could be committing a crime against humanity by blocking aid intended for up to 2.5 million survivors faced with hunger, loss of their homes and potential outbreaks of deadly diseases.

But signs have appeared that the generals might be listening to the chorus of criticism.

A team of 50 Chinese medics arrived in Yangon on Sunday night, following in the footsteps of medical personnel from India and Thailand, the official Chinese news agency Xinhua reported. On Monday some 30 Thai doctors and nurses began working in the delta — exceptions to the regime's ban on foreign aid workers in the area.

A senior British official hinted Sunday that a breakthrough may also be near that would allow foreign military ships to join the relief effort, but warnings grew of a potential second wave of deaths, this time among children who lack fresh water and proper shelter.

British Foreign Office Minister Lord Malloch-Brown told the British Broadcasting Corp. that he believes the rulers of Myanmar — also known as Burma — might soon relent and let Western military ships help out, especially if Asian go-betweens are involved.

Burma state-run media lashed out at critics of the regime's response to the disaster, detailing the junta's efforts. State television showed Than Shwe inspecting supplies and comforting homeless victims in relatively clean and neat rows of blue tents.

The media said Than Shwe traveled from the capital, Naypyitaw, to relief camps in the Hlaing Thar Yar and Dagon suburbs of Yangon.

Some survivors clasped their hands and bowed as he and a column of military leaders walked past. At least 78,000 people were killed in the May 2-3 storm and another 56,000 were missing.

The official New Light of Myanmar newspaper said the government's National Disaster Preparedness Central Committee will work with foreign aid agencies "to ensure that all relief funds and supplies reach the storm victims."

Burma will also work with ASEAN countries to help cyclone-stricken areas in a rehabilitation drive that will be planned over the next several days, the newspaper said, quoting Deputy Foreign Minister Kyaw Thu.

The situation remained grim in the Irrawaddy delta south of Rangoon.

In the delta city of Laputta, hundreds of children covered their heads from the rain with empty aluminum plates as they lined up in front of a private donation center. They were given rice, a spoonful of curry and a potato.

"Children only. Please. Children only," shouted a man who pushed back a crowd of adults. He explained they were feeding children and the elderly first because food supplies were limited and most adults could still fend for themselves.

Aid agencies have said about 2.5 million survivors are in desperate need of help — food, shelter from intermittent monsoon rains, medicines, clean drinking water and sanitation.

Shrestha, the UNICEF official, said the relief effort was impeded by a lack of logistical support. He said there are not enough trucks to transport supplies and a shortage of manpower to load and unload them.

"Many of those areas are still unaccessible because of the high water table, roads covered with fallen trees and bridges that are broken. The government has been clearing it but it's still not completely done yet," he said.

Appeals have gone out to donors, with limited responses.

The United Nations said only $41 million of its $201 million "flash appeal" has been contributed so far.

The Geneva-based International Red Cross has appealed for 52 million Swiss francs $51 million to fund its aid operation in Burma over the next three years, up from the $6.2 million it asked for immediately after Cyclone Nargis.