May 18 (Bloomberg) -- Myanmar's neighbors plan to provide more help to assist as many as 2.5 million people affected by Cyclone Nargis as aid groups and government leaders warn of a humanitarian catastrophe unless the country permits more aid.

Foreign ministers from the Association of Southeast Asian Nations will hold an emergency meeting in Singapore tomorrow to receive Myanmar's account of the disaster and discuss its refusal to allow most foreign relief experts into the country.

Myanmar has accepted only a trickle of the aid offered since the storm on May 3, barring most foreign staff and rejecting offers of helicopters and boats. China is backing Myanmar as it resists pressure from the U.S. and other nations to accept more assistance, saying countries must show ``due respect.''

``We want to push forward to help as much as possible,'' Tharit Charungvat, a spokesman for Thailand's foreign ministry, said by telephone today from Bangkok. ``We have to assess their needs, and we hope to do that tomorrow,'' Tharit said.

British Prime Minister Gordon Brown accused Myanmar's military regime yesterday of creating a ``man-made catastrophe'' with the refusal to accept international help. Jean-Maurice Ripert, France's envoy to the United Nations, said there was a risk of ``a true crime against humanity.''

`Rice Crisis'

``The scale of this is just extraordinary and two weeks on, we're only still coming to grips with its power,'' Reverend Tim Costello, chief executive officer of World Vision Australia, told Sky News Australia today. ``We are talking about a major food scarcity, a rice crisis, in the future.''

The cyclone is the worst natural disaster to hit Southeast Asia since the 2004 Indian Ocean tsunami, which killed more than 220,000 people. The death toll from the storm has reached almost 78,000, the Associated Press cited Myanmar state television as saying. An additional 56,000 people are missing.

Asean, the 10-country bloc that includes Myanmar, has become a target of criticism, with humanitarian groups and aid agencies calling on the group to do more. Asean's reaction to the crisis was disappointing, Agence France-Presse reported, citing Debbie Stothard, an activist with the anti-junta group Alternative Asean Network on Burma, the former name of Myanmar.

Singapore Foreign Minister George Yeo said the outcome of the ministerial meeting was unlikely to be ``dramatic,'' according to a report today in the Sunday Times, citing Yeo. There must be respect for ``the autonomy of countries,'' Yeo was cited as saying.

UN Mission

United Nations emergency-relief coordinator John Holmes is scheduled to arrive in Myanmar today to help expedite aid delivery, according to a report from the UN News Center. As many as 2.5 million people have been ``severely affected'' by the cyclone and need help, the report said.

``We are getting aid through,'' said Reverend Costello, the head of World Vision Australia, which has 600 workers trucking aid, and packing clothes, water and medicine to devastated areas. ``But I would liken it to having a three-inch pipeline of aid trickling when we need a 30-meter pipeline pumping.''

Rain is increasing the risk of water-borne diseases and World Vision is treating any sick person with antibiotics to ward off cholera, Costello told Sky News Australia.

Asean, formed in 1967, groups Brunei, Thailand, Vietnam, Singapore, Indonesia, Laos, the Philippines, Malaysia, Cambodia as well as Myanmar, which was admitted in 1997.

``We should leave that channel open for communication,'' Thailand's Tharit said. ``In fact, the prime minister of Thailand has conveyed a message to Myanmar's leaders on more access.''

To contact the reporters for this story: Nesa Subrahmaniyan in Singapore at nesas@bloomberg.net; Gavin Evans in Wellington at gavinevans@bloomberg.net

Last Updated: May 18, 2008 00:22 EDT