The country formerly known as Burma is near a "massive public health catastrophe," the British non-profit Oxfam said as survivors face a potential outbreak of waterborne diseases, The Washington Post reported Monday.

"The ponds are full of dead bodies, the wells have saline water and even things like a bucket are in scarce supply," said Sarah Ireland, Oxfam's regional director.

She appealed to the military junta, which has restricted the flow and distribution of relief supplies, to allow humanitarian agencies to send technical and health experts to help prevent any outbreak of disease.

The cyclone and subsequent tidal sea surge ripped across the low-lying Irrawaddy Delta just more than a week ago. The official death toll tops 28,000 but humanitarian officials said the tally could be greater. Thousands of people are missing.

Relief efforts were set back when a boatload of rice, drinking water, clothing and other items sank Sunday in the Irrawaddy Delta after it apparently hit a submerged tree, the International Federation of Red Cross and Red Crescent Societies said. The people aboard the vessel were safe.

Residents salvaged some of the supplies but river water contaminated the food, the organization said.

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