"We are willing to do this sacrifice, but for not free," Correa said. "This is an insignificant figure compared to what is spent on the Iraq war."

He said Ecuador would create a trust fund for donations. The government would also accept pardons of bilateral and multilateral lenders debt as payment.

Correa, an ally who has followed the nationalist wave led by Venezuelan President Hugo Chavez, says Ecuador will give donors until next year to make offers. Otherwise it will develop the oilfield, which could generate thousands of job in South America's fifth-largest oil producer.

The US$350 million Ecuador is seeking is about half of the annual revenues it believes it would make from the Ishpingo-Tambococha-Tiputini (ITT) oilfield, which the government says holds reserves of more than 1 billion barrels.

Part of the ITT oilfield is inside the 2,427-acre (982-hectare) Yasuni National Park, where Amazon isolated indigenous groups live alongside rare jaguars and river dolphins.

"We are asking the world to save life," Energy Minister Alberto Acosta said in a recent interview with Reuters.

Acosta said exploiting the fields' entire reserve would only provide 12 days of global oil consumption.

He has said Ecuador would sign an international treaty to assure foreign nations it will keep its part of the deal.

"This is a sacrifice and we are asking the world to stop consuming fuel for only 12 days, which is what will be extracted from the ITT," Acosta said.

Roger Tissot, an analyst with consultancy PFC Energy, said Ecuador faces an uphill battle to assure the international community it will keep its word.

"It is a crazy idea, but it doesn't mean its wrong," Tissot said. "The challenge for the idea is the credibility of the Ecuadorean government given its track record on keeping contractual agreements."