May 9 (Bloomberg) -- Myanmar's ``food basket'' bore the brunt of last week's cyclone and supplies in the nation are now threatened, the United Nations said as aid agencies told the junta to stop delaying emergency relief deliveries.

The five worst-affected states produce most of the fish, rice and pork for the nation's 47.8 million people, the UN's Food and Agriculture Organization said.

``Time is running out to prepare for the main rice planting season, which starts in early June,'' He Changchui, the FAO's chief for Asia and the Pacific, said in a statement yesterday.

The UN and Southeast Asian governments are calling on the ruling generals to issue travel visas to aid workers and admit planes loaded with food. Myanmar will distribute international supplies itself and ``is not ready to receive search and rescue teams as well as media teams from foreign countries,'' Agence France-Presse cited the government as saying today.

``Myanmar has prioritized receiving emergency relief provisions and is making strenuous efforts to transport those provisions without delay by its own labors to the affected areas,'' the Foreign Ministry said in a state newspaper, according to AFP.

About 276,000 of the 1.5 million people needing aid received it as of May 7, Richard Horsey, a spokesman for the UN disaster response unit, said in Bangkok today.

Boats, Helicopters

``There is only a small window of opportunity if we are to avert the spread of diseases that could multiply the already tragic number of casualties,'' said Noeleen Heyzer, the top UN official in the Asia-Pacific.

Myanmar's state media reported that at least 22,000 people have died and more than 40,000 are missing and a U.S. diplomat in Yangon estimated the death toll may rise to 100,000.

The junta must ``issue visas expeditiously, and if possible, exempt all visa requirements for all UN aid workers, so that aid can reach the people,'' Heyzer said in a statement.

Only a handful of visas have been issued by the military that has ruled the country formerly known as Burma since 1962.

A Boeing 747-400 from China, a key ally of Myanmar, landed at Yangon International Airport today carrying supplies including medicine, tents, food and water-purification tablets, China's official Xinhua news agency reported. The government in Beijing will send additional relief supplies tomorrow, the news agency cited unidentified government officials as saying.

Red Cross

The International Federation of the Red Cross and Red Crescent Societies flew in 6 tons of shelter supplies to Yangon from Kuala Lumpur yesterday and will send a further 8 tons from Bangkok today, spokesman John Sparrow said by telephone from the Malaysian capital.

Myanmar's southern Irrawaddy delta was swamped by a surge of water as high as 12 feet (3.5 meters) when Tropical Cyclone Nargis struck May 3. The country will experience rain, some of it torrential, in the next few days, according to forecaster AccuWeather.com.

The Association of Southeast Asian Nations said it is trying to persuade Myanmar, a member of the group, to relax border controls.

Thailand's Prime Minister Samak Sundaravej said today he will visit Myanmar May 11. The premier promised the U.S. ambassador yesterday he would do so if he failed to persuade the junta in talks by telephone to allow U.S. aid shipments, government spokesman Wichianchote Sukchotrat told reporters.

Trickling In

``Aid right now is going in at a trickle,'' Anne Richard of the U.S.-based International Rescue Committee said in an interview With Bloomberg Television today. ``Without the permissions to go into the country the whole system is grinding to a halt.''

Queues for fuel in Yangon have stretched as long as 5 kilometers (3 miles), said James East, a Bangkok-based spokesman for the Christian relief group World Vision. Nails, zinc sheeting and other provisions for repairing housing have become unaffordable for most people, he said.

Myanmar deported a search and rescue team and media who arrived on a May 7 flight from Qatar because it expected the plane to carry emergency aid, not workers, AFP cited the Foreign Ministry as saying.

Myanmar has been under international sanctions since the military rejected the results of elections in 1990, won by Aung San Suu Kyi's National League for Democracy.

The junta plans to press ahead with a referendum tomorrow for a new constitution before elections in 2010. The ballot will be delayed until May 24 in the worst-affected areas.

UN Secretary-General Ban Ki-moon suggested yesterday that Myanmar delay the vote.

``It may be prudent to focus instead on mobilizing all available resources and capacity for the emergency response efforts,'' he said a statement released by the UN in New York.

The NLD called on the junta to postpone the vote, AFP reported from Yangon today.

``It is not the appropriate time to hold the referendum,'' AFP cited spokesman Nyan Win as saying. Suu Kyi remains under house arrest.

To contact the reporters on this story: Michael Heath in Sydney at mheath1@bloomberg.net; Simeon Bennett in Singapore at sbennett9@bloomberg.net.

Last Updated: May 9, 2008 03:56 EDT