More than $300m (£188m) has been promised to stop the exploitation of 846m barrels of oil below the Yasuní national park in Ecuador, one of the world's most biologically rich areas of rainforest, new figures show.

Ecuador's idea to leave the oil in the soil under the Ishpingo-Tambococha-Tiputini (ITT) area of the park and ask the world to compensate it with half its monetary value was hailed as a revolutionary, if idealistic, new conservation idea when it was first proposed in 2007.

But critics doubted whether raising the $3.6bn needed in 13 years would be possible, and accused Ecuador of holding the world, literally, over a barrel.

However, figures released by the UN Development Programme-run Yasuní-ITT initiative shows that while most wealthy governments have declined to contribute, foundations, individuals and cash-strapped regional authorities in austerity-hit Europe have pledged or given over $300m since 2011, when the fundraising drive began in earnest.

Germany has offered $50m over three years, and Chile, Colombia, Georgia and Turkey have given token amounts. In addition, 10 regions of Europe have contributed $150-250,000 each, along with corporations including Coca Cola, airlines, banks and Brazilian, US and Russian foundations. A Puerto Rican musician gave $50,000.

But while only $64m has been formally deposited, the papers show $187m has been promised by countries including Belgium, Brazil, France, Lebanon, Indonesia, Turkey, Spain and Qatar. Some is likely to come via debt swaps and "technical agreements" as well as contracts and agreements with companies.

"What we have on the Yasuní's land is far more than we have underground. We have been going just one year and we are on track to save the forest. What has pushed governments like Germany and France has been people. In Germany over 100,000 people signed a petition in a week," said the head of the negotiating committee of the Yasuní-ITT, Ivonne Baki.

"Ecuador does not want to be depend on oil and this is a way to reduce dependency. Oil countries are cursed. Developing countries depend on it so much that they do not develop anything else. It breeds corruption and the poor pay the price. The only benefit traditionally go to the elites," said Baki.

She disclosed that unnamed corporations had offered Ecuador "very large" sums to be linked to Yasuní but had been turned down. Guatemala, Madagascar, Nigeria and other African countries have considering replicating the "leave the oil in the soil" idea, she said.

Money is not given directly to the Ecuadorean government but is held in trust funds and administered by the UN Development Programme working with a board made up of indigenous peoples, local communities, academics and others.

Money from the capital raised will go to renewable energy projects whose profits will go to support reforestation and conservation, as well as social projects.

So far, nine hydroelectric and several solar and geothermal projects have been lined up to receive money.