The number of people in Myanmar who have died in the wake of Typhoon Yagi rose to more than 220, with nearly 80 others still missing, the military government said.
The storm swept through northern Vietnam, Laos, Thailand and Myanmar last week, killing more than 500 people across the region, according to official figures.
It triggered severe floods and mudslides in Myanmar, leaving at least 226 dead as whole villages were wrecked.
With hundreds of thousands of acres of crops destroyed, the UN also warned that more than half a million people in the war-torn country are in urgent need of food as well as drinking water, shelter and clothes.
The UN said the storm's devastation spanned nine states and regions, including the the country's capital Naypyidaw in the interior, as well as Mandalay to the north, Magway to the west, and Bago to the south - regions that lie along the Irrawady, Myanmar's largest river.
Also hit were Shan State in the north-east and Mon, Kayah and Kayin states, which lie to its south.
A civil war has engulfed the country since early 2021, when the army sized power after ousting the democratically-elected government.
Since then thousands have been killed and millions forced from their homes as various armed resistance groups battle the ruling military junta.
In the last year or so, the army has lost control of large parts of the country, creating an unstable patchwork of governance.
That, coupled with poor communication in remote areas, has meant information about casualties has been slow to emerge.
The United Nations said the floods are among the worst in Myanmar's recent history. Its disaster response agency estimated that some 630,000 people have been affected by the flooding with blocked roads, damaged bridges and severed communication lines, all of which have severely hampered relief efforts.
Aid agencies also have little or no access to many parts of the country, including Shan State, one of the worst-hit by the flooding, which is now largely controlled by a rebel army.
A volunteer rescuer in the state's south told BBC Burmese that entire homes had been buried under mudslides.
"We have collected over 100 dead bodies so far, including children and elderly people. We're still searching for over 200 more," he added.
“This flooding is the worst I have ever seen in my life,” said a resident in the east of Shan State.
The situaiton is just as dire more than 500 miles away, in the south-east: “People are in urgent need of food," Khon Matia, a senior official in rebel-controlled Kayin State (formerly Karen State) told BBC Burmese.
"There is no offer of international aid. People are in a more difficult position here because everything is blocked because of the floods and the war. So it is very difficult to reach us."
The ruling military junta issued a rare appeal for help at the weekend, with neighbouring India so far the only country to respond. It sent aid, including food, clothes and medicine.
Typhoon Yagi also caused 10 deaths in Thailand and one in Laos.
In Vietnam, the death toll stands at 292, with 38 missing, more than 230,000 homes damaged, 280,000 hectares of crops destroyed and major manufacturing hubs heavily damaged, according to authorities.