YANGON - UN humanitarian chief John Holmes arrived in Myanmar on Tuesday for a three-day trip to see how the military-run nation is coping after a devastating cyclone, a UN spokesman said.

After his morning arrival in Yangon, Mr Holmes took a helicopter straight to areas of the Irrawaddy Delta worst-hit by Cyclone Nargis, which left about 138,000 people dead or missing when it battered southern Myanmar in early May.

'Mr John Holmes arrived in Yangon and left for the delta already. He's accompanied by the deputy foreign minister and other officials', United Nations spokesman Laksmita Noviera said.

Mr Holmes, who flew in from Singapore where he attended a meeting of the Association of South-east Asian Nations (Asean), will return to Yangon later on Tuesday and meet with aid workers and donors on Wednesday.

On Thursday, he will travel to Myanmar's isolated new capital Naypyidaw to meet with government representatives, the UN said, before leaving the country.

A Myanmar government official said Mr Holmes will likely be granted a meeting with Prime Minister Thein Sein, but Ms Noviera was unable to confirm which officials Holmes will be holding talks with in the capital.

This will be the envoy's second visit to Myanmar since the cyclone hit, causing major damage to parts of the country's infrastructure and creating a humanitarian emergency.

Myanmar's ruling generals - wary of any outside interference - at first blocked entry to many foreign aid workers and relief shipments, and only relented after a personal visit by UN Secretary General Ban Ki Moon.

Asean on Monday released a report saying that rebuilding Myanmar's cyclone-devastated south and bringing aid to millions of survivors will cost one billion dollars over the next three years.

Mr Holmes told the Asean meeting that the relief operation was still ongoing in impoverished Myanmar, and urged donors to come forward with funds to help the nation to rebuild.