At least 22,000 people are confirmed dead following the weekend's cyclone in Burma.
It is estimated that another 41,000 are missing and hundreds of thousands remain homeless and without water.
Aid workers are racing to deliver food and water to the worst-hit Irrawaddy delta region, which was submerged by floodwaters, leaving scenes of devastation.
The Irish Government has made €1m available for disaster relief, while the US has offered $3m (€1.9m) in aid.
In the first news conference since tropical cyclone Nargis hit the Irrawaddy river delta, the government said a 3.5m tidal wave killed many people.
'More deaths were caused by the tidal wave than the storm itself,' Minister for Relief and Resettlement Maung Maung Swe told reporters in the devastated former capital, Rangoon, where food and water supplies are already running low.
'The wave was up to 3.5m high and it swept away and inundated half the houses in low-lying villages,' he said, giving the first detailed description of the weekend cyclone. 'They did not have anywhere to flee.'
It is the worst cyclone to hit Asia since 1991, when 143,000 people died in Bangladesh.
Earlier, Foreign Minister Nyan Win said on state television that 10,000 people had died in Bogalay, a town 90km southwest of Rangoon.
Reflecting the scale of the disaster, the ruling junta said it would postpone to 24 May a constitutional referendum in the worst hit areas of Rangoon and the sprawling Irrawaddy delta.
However, the broadcast said the 10 May vote on the charter, part of the army's much-criticised 'roadmap to democracy', would proceed as planned in the rest of the southeast Asian nation, which has been under military rule for the last 46 years.
The government also lifted states of emergency in three of the five states and some parts of the worst-hit Rangoon and Irrawaddy regions.
After a meeting with Burma's ambassador to Bangkok, Thai Foreign Minister Noppadol Pattama said he had been told 30,000 people were missing after Saturday's devastating storm.
'The losses have been much greater than we anticipated,' he said. Ambassador Ye Win declined to speak to reporters.
The total left homeless by the 190km per hour winds and 3.5m storm surge is in the several hundred thousands, UN aid officials say.
The scale of the disaster in the military-ruled southeast Asian nation drew a rare acceptance of outside help from the diplomatically isolated generals, who spurned such approaches in the aftermath of the 2004 Indian Ocean tsunami.
