©AFP/Khin Maung Win

A cyclone survivor carried away useable articles from the debris of destroyed houses in Kyauktan, Burma

An estimated 1.5 million Burmese are on the brink of a "massive public health catastrophe," the British charity Oxfam warned yesterday, as desperate survivors of Cyclone Nargis poured out of the devastated Irrawaddy Delta into regional towns in search of water, food, and other help.

Burma is facing a "perfect storm" of conditions that could lead to an outbreak of waterborne disease, said Sarah Ireland, Oxfam's regional director.

"The ponds are full of dead bodies, the wells have saline water, and even things like a bucket are in scarce supply," Ireland said. She appealed for Burmese authorities, who have restricted access to the country, to allow humanitarian agencies to send in technical and health specialists to help prevent disease outbreaks.

The struggling relief efforts suffered another setback when a boat ferrying rice, drinking water, clothing and other aid supplies sank in the delta early yesterday, apparently after hitting a submerged tree, the International Federation of Red Cross and Red Crescent Societies said.

Residents were able to salvage some of the supplies, meant for more than 1,000 survivors, but river water probably contaminated the food, the organization said. All of those aboard made it safely to land. The boat was carrying one of the first international aid shipments.

"This is a great loss," said Aung Kyaw Htut, who is supervising the distribution effort. "This would have been our very first river shipment, and it will delay aid for a further day."

The cyclone and tidal sea surge ripped across the low-lying delta a week ago, with winds topping 120 miles per hour. The country's ruling junta yesterday raised its official tally of the dead to more than 28,000, though humanitarian specialists say the toll could be much higher. Thousands remain missing.

The dire warnings came as Burma's state media declared success in a referendum to secure public endorsement of a new constitution that critics say would legitimize military rule. Burma's leaders say the charter will lay the foundation for a "discipline-flourishing democracy."

With conditions in the delta increasingly desperate, many survivors began besieging small towns, searching for help. In the town of Laputta, which lost 85 percent of its buildings, about 28 makeshift camps have sprung up. But supplies are limited.

UN agencies and international charities that were operating in Burma before the disaster have been slowly setting up operations. Emergency supplies are gradually arriving in the country and just beginning to reach the low-lying Irrawaddy Delta, but is far short of what is needed.

"Time is really of the essence. Already we have seen a diarrhea outbreak in the very urban areas of [Rangoon], and with cyclones you'd usually see pneumonia soon as well, and also malaria because of the standing water," said Naida Pasion, the Burma program director for Save the Children, which has a staff of 500 there.

The World Food Program, which on Friday accused authorities of impounding planeloads of emergency food, said cargo and materials sent since then had been released and sent to the disaster zones. The International Committee of the Red Cross also sent a planeload of relief supplies yesterday, including body bags.

Yet a week on, most survivors have not yet received any help, because of the lack of supplies and logistical difficulties.

"Beyond the main arterial roads, it's a massive challenge, not only because the flood waters are still there, but also because even when they are not, it's extremely difficult to navigate," said Marcus Prior, spokesman for the World Food Program.

The Burmese army insists that it can manage the massive relief operation and has rebuffed offers from the United States, its longtime critic, and countries in the region for military assistance to distribute relief supplies.

But for years, Burma's military has struggled to feed its own. Vegetables are often grown alongside the runways of army airfields, and chicken coops are usually kept behind barracks across the country, which the junta renamed Myanmar. It's not that the soldiers are keen to play farmers. But troops in far-flung places have long been ordered to "live off the land" because the army command has been unable to reliably supply its 400,000-member force with the food it needs.

"The logistical system in Burma is so shaky that in the 1990s, they told regional commanders and bases outside Rangoon [the country's main city] that they had to take care of their own logistics" for basic needs, said a Western analyst who has studied Burma's military.

Military analysts warn that Burma's army has neither adequate equipment nor training to cope with the crisis, and its insistence on going it alone - or through their own "strenuous labor" as state media call it - could cost many lives.

"Disaster relief operations, like any military operation, require training, practice, and equipment," said Robert Karniol, a regional defense writer. "Even if they were well practiced, they would have difficulties responding because of the scale."

Humanitarian groups are reluctant to cooperate with foreign militaries in disaster response. But the 2004 tsunami and the 2005 earthquakes in Pakistan demonstrated how foreign militaries could use their highly specialized transportation equipment to move large quantities of supplies to hard-to-reach areas.

The Irrawaddy Delta presents the type of logistical challenge best suited for military hardware. Vast areas remain submerged, accessible only by boat or helicopter, and the region's ports are inaccessible to civilian ships as a result of the damage.

"The Myanmar military has certain assets, but in a response this size, you need to start using everything you've got," said Sebastian Rhodes Stampa, a civil-military liaison officer with the UN Office for the Coordination of Humanitarian Affairs.