BANGKOK, May 4 (Reuters) - It will take several days to assess the scale of damage wrought by a large tropical cyclone that slammed into Myanmar's main city, Yangon, and outlying areas, a top U.N. official said on Sunday.

"There does not seem to be a high number of casualties but for sure there is a lot of damage to property and infrastructure," Therje Skavdal told Reuters in Bangkok.

"It's early and it will take a few days before we get an overview of the damage," said Skavdal, regional head U.N. office for the Coordination of Humanitarian Affairs (UNOCHA).

Cyclone Nargis, a Category 3 cyclone packing winds of 190 km (120 mile) per hour, ploughed through the heart of the sprawling river delta city of 5 million on Saturday, felling trees and powerlines and cutting off phone lines and the Internet.

State media confirmed on Sunday that 4 people were killed in Yangon, but there was no word on casualties in the worst-hit Irrawaddy delta region.

Skavdal said communications with the U.N. team in Yangon was a "major challenge", but they had some contact via mobile phones.

U.N. agencies and the International Red Cross in Myanmar had stockpiled food and other supplies ahead of the storm and UNOCHA officials would meet in Bangkok later on Sunday to assess the situation.

Formerly called Burma, Myanmar has been run by a secretive military junta for the last 46 years and places restrictions on the movements and access of the few aid agencies allowed into the country. (Reporting by Darren Schuettler; Editing by Ed Cropley and Bill Tarrant)

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