Aid call as Burma casualties rise.

International agencies are pushing to gain access for a massive aid operation in Burma, where the toll from Saturday's cyclone continues to rise.

Many thousands of people are said to have died in the disaster, and many more are missing, officials say. Hundreds of thousands of people are said to be without clean water and shelter, with some areas still cut off. Burma's leaders say they will accept external help, in a move correspondents say reflects the scale of the disaster.

The military junta has said it will postpone to 24 May a referendum on a new constitution in areas worst-hit by the cyclone - including the former capital Rangoon and the Irrawaddy Delta, state television said on Tuesday. But the vote initially planned for 10 May will proceed as planned in the rest of the country, the report said.

Work is still under way to assess the scale of the devastation caused by Cyclone Nargis, which brought winds reaching 190km/h (120mph). More deaths were caused by the tidal wave than the cyclone itself, Minister for Relief and Resettlement Maung Maung Swe told a news conference in Rangoon on Tuesday.

"The wave was up to 12ft (3.5m) high and it swept away and inundated half the houses in low-lying villages," he said. "They did not have anywhere to flee."

Some 95% of the homes in the city of Bogalay in the Irrawaddy river delta were destroyed, he added. Prices of food, fuel and basic necessities have also risen dramatically in the wake of the storm, putting more people at risk. Secretary-General Ban Ki-moon said the UN would do "whatever [necessary] to provide urgent humanitarian assistance".

A shipment of aid from Thailand is due to arrive on Tuesday and India is sending two naval vessels. The US has also offered to increase aid offered if Burma agrees to allow a US team access to assess the situation.