Yangon  - United Nations Secretary-General Ban Ki-moon arrived in Myanmar on Thursday to inspect areas devastated by Cyclone Nargis, which hit the country's coastal region 20 days ago, and talk to the ruling junta about speeding up disaster relief for the people.

Ban, who arrived at Yangon International Airport on THAI Airways flight, was tentatively scheduled to visit the Irrawaddy delta, the area hardest hit by Cyclone Nargis on May 2-3.

Myanmar Foreign Minister Nyan Win and UN officials were at the airport to greet Ban.

"It's most likely that he's going to the Irrawaddy delta but his itinerary is changing every minute," said Aye Win, spokesman for the UN Information Centre in Yangon. It has been estimated that nearly 60 per cent of the Irrawaddy's infrastructure was destroyed or damaged by the storm.

The region is also Myanmar's traditional rice bowl, accounting for the lion's share of the annual rice crop which needs to planted in coming weeks.

At a press conference in Bangkok Wednesday, Ban said he was going to Myanmar "to see for myself the affected areas and to meet the people who are in need."

Almost three weeks after the cyclone hit Myanmar, an international disaster relief effort has only been able to reach about 25 per cent of the 2.5 million people affected by the storm, Ban noted.

According to Myanmar government estimates the cyclone left at least 133,000 dead or missing, ranking it as the worst natural calamity in the reclusive country's history.

The disaster has also brought in to the world spotlight Myanmar's rulers, a military dictatorship that has lorded over its people for the past 46 years, earning the country pariah status among Western democracies and proving an embarrassment for even its closest Asian allies.

The State Peace and Developemnt Council (SPDC), as the junta styles itself, has drawn international criticism for failing to facilitate international aid for its own people in the aftermath of Cyclone Nargis, and for refusing to hand out more visas to foreign aid workers and allow those inside the country to work in the most affected areas such as the Irrawaddy delta.

Ban is scheduled to meet with "high level" government authorities in Yangon Thursday, before heading to the military's new capital of Naypyitaw, about 350 kilometres north of Yangon, on Friday to hold talks with junta head Senior General Than Shwe.

The UN chief said his priority for the trip as to "expedite all arrangements for facilitating the free movement of international relief aid and workers."

He will return to Bangkok Friday night in order to hold talks on Saturday with Thai Prime Minister Samak Sundaravej and other Thai ministers.

Thailand, which is Myanmar's eastern neighbour, has turned into the main logistical and organizational hub for the international relief effort currently underway.

While thanking the Thai authorities, Ban said on Wednesday that he wanted to set up forward logistical bases inside Myanmar as well, "in coordination with the government, to speed up the delivery of supplies and better coordinate our mutual assistance efforts."

The UN secretary-general will return to Yangon on Sunday to preside over a UN-ASEAN pledging conference for Myanmar, for the country's short-term and long-term needs.

On Monday, ASEAN (Association of South-East Asian Nations) agreed to act as a liaison between the international aid community and Myanmar's junta. The grouping includes Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.

Myanmar Foreign Minister Nyan Win has estimated losses to Cyclone Nargis at more than 10 billion dollars. (dpa)