A satellite photo shows the storm over Burma. (NASA/MODIS)

More than 351 people were killed and thousands of homes were destroyed by a powerful cyclone that swept through Burma, state-run television said Sunday.

Reports say the capital and four other regions of the country, also known as Myanmar, have been declared disaster zones.

Tropical cyclone Nargis packed winds of nearly 200 km/h when it hit Saturday morning, toppling trees, downing power lines and littering the streets with debris.

The military government said 50 per cent of buildings were damaged or collapsed in the worst hit areas.

The storm packed winds of nearly 200 km/h and knocked out electricity in much of Rangoon, the country's commercial capital. (Associated Press)

Chris Kaye, the United Nations' acting humanitarian co-ordinator in Rangoon, said thousands of homes were destroyed in the Irrawaddy delta because of the storm surge, along with high winds and rain.

He said the UN planned to send teams Monday to assess the damage. Initial assessment efforts have been hampered by roads clogged with debris and downed phone lines.

The state-owned newspaper New Light of Myanmar reported Sunday that the international airport in Yangon remained shut. Domestic flights have been diverted to the airport in Mandalay, it said.

The cyclone hit at a delicate time for the country's military-led government, less than a week ahead of a crucial referendum on a new constitution.

Should the junta be seen as failing disaster victims, voters who already blame the government for ruining the economy and squashing democracy could take out their frustrations at the ballot box on May 10.

With files from the Associated Press