Prince Charles visited Hampton Court Palace last night to tell a gala dinner preserving rainforests was "the biggest single and immediate opportunity" to combat climate change.

Speaking at the dinner for the WWF, the prince said that ways needed to be found to put a value on rainforests, which made them worth more to preserve than cut down.

He said the world's forests stored carbon, acted as a natural thermostat on the climate, gave moisture to the atmosphere and sustained the lives of 1.4billion of the poorest people in the world.

But he warned the audience at the dinner that rainforest destruction was taking place at a "truly terrifying pace".

"Every year 50million acres, an area the size of England, Wales and Scotland combined, are destroyed or degraded," he said.

He told the WWF event emissions from burning forests were responsible for around 20 per cent of global greenhouse gases, with only the energy sector emitting more.

"The simple fact is that combating deforestation is likely to be one of the quickest and cost effective means of reducing carbon dioxide emissions," he said.

Charles announced the creation of Prince's Rainforests Project, which aims to work with the private sector, governments and environmental experts to find solutions which could be put in place within the next 18 months.

"These solutions need to provide credible incentives to rainforest nations, down to the farmers on the ground, and must 'out-compete' the drivers of rainforest destruction," he said.

The Prince also backed the WWF's new Amazon Initiative, which will work in the nine countries where the South American rainforest grows - Brazil, Peru, Bolivia, Columbia, Venezuela, Guyana, Ecuador, Suriname and French Guyana.

Before making his speech at the dinner, Charles met samba dancers and listened to drummers who played traditional Brazilian rhythms.