Guyana and Norway yesterday hailed a historic agreement that will see the Scandinavian country invest $250m (£150m) to preserve the rainforests of the Latin America nation. With world leaders warning that no legally binding agreement will be possible at the climate summit in Copenhagen next month, the two comparative minnows completed one of the biggest forest conservation deals ever signed.

Both sides signalled their intention to "provide the world with a working example of how partnerships between developed and developing countries can save the world's tropical forests," they said in a joint statement.

The former British colony, sandwiched between Venezuela and Brazil, is home to fewer than a million people but it also boasts an intact rainforest larger than England. In 2007 Guyana's president Bharrat Jagdeo made an unprecedented offer to to place its entire standing forest under the control of a British-led international body in return for a bilateral deal with the UK to secure development aid and the technical assistance needed to switch to a low carbon economy.

Despite a number of false starts and assurances that it was considering the offer – first publicised in The Independent – Downing Street failed to make any concrete progress, leaving the way clear for oil-rich Norway to seize the opportunity.

Speaking yesterday during a visit to London, President Jagdeo said that public pressure was vital on rich, polluting countries to "help progressive politicians to deliver results on climate change". While avoiding criticism of the UK government, the Guyanese leader thanked those who had brought the country's rainforest offer into the international arena.

"The Independent was key to getting our original message to the public, and this kind of campaigning journalism will be vital in the years to come," he said.

Countries like Guyana, whose capital Georgetown is extremely vulnerable to rising sea levels, have contributed next to nothing to the heat- trapping gases in the atmosphere that cause global warming. Yet they will be among the first victims of a changed climate and have been seeking ways to preserve the vast carbon sinks of their tropical forest without sacrifcing development in a country where many live in abject poverty.

Under the terms of the agreement with Norway, Guyana will accelerate its efforts to limit forest-based greenhouse gas emissions and protect its rainforest as an asset for the world. Norway will provide financial support of up to $250m over five years in line with the Jagdeo administration's success in implementing limiting emissions and halting deforestation.

"Through this partnership, we are building a bridge between developed and developing countries," said Norway's Minister of the Environment and International Development Erik Solheim. "We are giving the world a workable model for climate change collaboration between North and South. It's not perfect, but it's good, and it will be improved upon as we learn and develop together."

The accelerating destruction of the rainforests that form a cooling band around the earth's equator is recognised as one the main causes of climate change.

Tropical deforestation accounts for one-fifth of all carbon emissions, more than the entire transport sector – including the aviation industry. The landmark Stern Review concluded that forests offer the single largest chance for cost-effective and immediate reductions of carbon emissions.