By Thin Lei Win

BANGKOK, July 24 (Reuters) - Aid agencies in cyclone-hit Myanmar will have to charter their own planes after the United Nations ends free flights between Yangon and Bangkok on Aug. 10, a senior U.N. official said on Thursday.

However, the five remaining helicopters ferrying supplies to remote areas in the hardest hit Irrawaddy Delta would continue to operate, U.N. humanitarian chief John Holmes said.

He said the temporary nature of the air bridge -- established between the Thai capital and Myanmar's biggest city in the weeks after the May 2 disaster -- was understood by aid agencies.

"It doesn't mean there will be no more aid flights," Holmes told reporters in Bangkok after a 3-day trip to assess aid operations in the former Burma.

"NGOs have to take on the responsibility to transport the aid themselves," he added.

Recovery from a cyclone that left at least 138,000 dead or missing, will cost more than $1 billion, a report by the United Nations and southeast Asian nations said.

The estimate, released on Monday at a meeting of foreign ministers of the Association of South East Asian Nations (ASEAN), covers the most urgent needs such as food, agriculture and housing for the next three years.

"It's a relief to confirm there is no mass starvation, or outbreaks of epidemics," Singaporean Foreign Minister George Yeo told a news briefing. "But there is a need for help -- we need money, we need assistance."

He said the country would need everything from clean water and building works to boats, fishing nets and buffaloes.

The United Nations appealed earlier this month for more than $300 million in additional aid for the former Burma, on top of $178 million already provided by donors.

Myanmar's secretive military government lifted restrictions on foreign aid workers after a visit in late May by U.N. Secretary-General Ban Ki-moon.

Without the Bangkok-Yangon flights, aid agencies will have to rely on sea routes for transport, and then travel by road to worst-affected areas.

"It's a more normal mode of operations instead of the emergency mode. It doesn't mean the relief needs are not there. It just means we can do it in a cheaper and more systematic way," Holmes said.

Holmes visited affected communities in the delta as part of a helicopter tour of the region. He also travelled to the new capital, Naypyidaw for talks with the military government.

"I was encouraged by the visit, by the progress that had been made, but obviously there is absolutely no room for complacency at this point in time," he said. (Editing by Darren Schuettler)

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