In the former capital, many roofs were ripped off even sturdy buildings, suggesting damage would be severe in the shanty towns that lie on the outskirts of the city of 5 million people.
State television was still off the air in Yangon and clean water was becoming scarce. Most shops had sold out of candles and batteries and there was no word when power would be restored.
In one western suburb, a group of 100 monks led efforts to clear streets littered with fallen trees and debris from battered buildings, a witness said.
"The clean-up is beginning but this will take a long time. The damage around town is intense," one Western diplomat told Reuters from Yangon, where the airport reopened on Monday.
State media said 19 people had been killed in Yangon and 222 in the delta, where weather forecasters had predicted a storm surge of as much as 12 feet (3.5 metres)
Only one in four buildings were left standing in Laputta and Kyaik Lat, two towns deep in the rice-producing region.
Some 90,000 people were homeless on the island of Haingyi, around 200 km southwest of Yangon on the fringe of the delta.
However, the carnage left by Nargis has not derailed a May 10 referendum on a new army-drafted constitution.
"The referendum is only a few days away and the people are eagerly looking forward to voting," the junta said in a statement confirming the vote would go ahead as planned.
The charter is part of a "roadmap to democracy" meant to culminate in multiparty elections in 2010, but critics say it allows the army to retain an unacceptable degree of power.
Bunkered down in their new capital, Naypyidaw, 240 miles to the north of Yangon, the junta's top brass has not formerly responded to an offer of international assistance.
But Myanmar's Minister of Social Welfare told U.N. officials help may be welcomed, depending on the terms, Skavdal said.
"I think it's a positive sign. As long as we are in dialogue it is good," he said.
Shunned by the West for its detention of democracy icon Aung San Suu Kyi and dismal human rights record, Burma has been the target of Western sanctions for years.
It receives far less foreign aid - about $2.50 per capita - than regional neighbours Cambodia ($47) and Laos ($63) and below the $14 average for low-income nations.
