* Military holds rare election to approve new constitution
* U.N. appeals for $187 million in aid
* U.N. food agency resumes relief flights
* U.S. says it has approval to send one aid flight
* "Second disaster" looms for survivors from disease (Adds colour on refugees; edits)
By Aung Hla Tun
YANGON, May 10 (Reuters) - Myanmar held a rare election on Saturday to approve a new army-drafted constitution, ignoring calls from the outside world to postpone the vote amid the devastation wreaked by Cyclone Nargis.
More than a week after Nargis (Daffodil) tore through the Irawaddy Delta, packing 190 kph (120 mph) winds that whipped up a wall of sea-water pulverising everything it its path, aid was barely dribbling to 1.5 million increasingly desperate survivors.
Health experts warned that a "second disaster" loomed from diseases such as diarrhoea and malaria, even if survivors of the cyclone that left tens of thousands killed or missing do manage to find food and shelter.
State-run TV repeatedly told citizens it was their "patriotic duty" to approve the new constitution that enshrines a dominant role for the military, which has ruled the country of 53 million since a 1962 coup.
"I voted yes. It was what I was asked to do," 57-year-old U Kyaing told Reuters in Hlegu, 50 km (30 miles) northeast of the cyclone-ravaged former capital, Yangon.
Even before Cyclone Nargis hit on the night of May 2, groups opposed to military rule, and foreign governments led by the United States, had denounced the constitution and vote as an attempt by the military to legitimise its 46-year grip on power.
The government’s feeble response to the disaster has only fed cynicism about the junta’s determination to proceed with their "roadmap to democracy" leading to multi-party elections in 2010.
UN AID APPEAL
The United Nations appealed for $187 million in aid, even though it is still not confident the food, water and tents flown in will make it to those most in need due the junta’s reluctance to admit international relief workers.
During an emergency meeting in New York on Friday, dozens of U.N. envoys voiced concern at the difficulties aid workers were having getting in. But Myanmar’s delegate insisted food and other supplies were being sent where needed upon arrival.
"We are ready to cooperate fully," Ambassador Kyaw Tint Swe told the meeting. "Regarding access, we hear you and I will certainly report back to the authorities."
The U.N.’s World Food Programme briefly suspended its aid airlift after it said 38 tonnes of biscuits and medical supplies were impounded at the airport in Yangon.
The generals approved one U.S. aid flight, due to arrive as soon as Monday carrying water purification systems and supplies to ward off waterborne diseases, U.S. officials said.
The Americans say they are preparing the same kind of assistance they provided after the 2004 Asian tsunami and the 2005 Pakistan earthquake. But the air bridge the U.S. military set up during the tsunami is unlikely to be replicated.
Myanmar has long been suspicious of the outside world, which the junta fears could bring in destabilising ideas and values, such as Western concepts of democracy and human rights.
The junta has brutally suppressed any sign of dissent. At least 31 people were killed when troops crushed monk-led pro-democracy protests last September.
While they have proved impervious to Western economic sanctions over their human rights record, the generals have avoided total isolation by using Myanmar’s vast natural gas reserves to befriend energy-hungry China and India.
Yet with each day that passes, pressure is mounting on the junta to admit a massive international relief operation before starvation and disease swell the death toll even more.
"This is the second disaster," Greg Beck, Southeast Asia programme director for the International Rescue Committee, told Reuters. "First was the cyclone and the surge of water, the second will come if there is no access to food, water and shelter. They will start dying," he said.
Myanmar has not updated the official toll since Tuesday, when it said nearly 23,000 were dead and 42,000 missing. The chief U.S. diplomat in Myanmar has said the toll could reach 100,000.
Hungry and desperate cyclone refugees have been pouring into towns from the devastated Irrawaddy delta taxing already stretched local resources.
"How many more days are we going to be able to feed them?" one businessman told Reuters on Saturday in Myaung Mya, a town of about 100,000 people about 70 km (45 miles) north of the coastline and out of the storm’s direct path when it hit.
"People here can barely afford to feed themselves."
The U.S. Navy is sending four ships on exercises in Thailand towards Myanmar. France said it was sending a naval ship carrying heavy-lift helicopters and 1,500 tonnes of aid, which would arrive by the middle of next week.
State-run TV in Myanmar warned of "foreign interference" in a repeatedly broadcast message urging people to cast their ballots for the new constitution. Voting in cyclone-devastated areas, including Yangon, has been postponed for two weeks.
The broadcast showed five young women performers in colourful clothing and singing songs, including the lyrics: "let’s go voting" and "come along for voting" with upbeat background music.
"To approve the state constitution is the national duty of the entire people today," messages in Burmese and English said.
A written message on the screen said: "Let us all who oppose foreign interference and manipulation; oppose puppet government with strings of colonialists. Vote Yes."
Most people are expected to do just that. Of the 20 people Reuters interviewed near polling stations in Hlegu, only two admitted to voting no. Even then it was in a whisper and with a nervous glance over the shoulder first.