Carbon dioxide is one of the main gases causing climate change, scientists say, and such exchanges are one way to offset carbon emissions.

Polluting industries in rich countries pay for clean development projects in poor countries.

Some forecasts warn that Africa will be badly affected by climate change, even though most of the greenhouse gases which cause it are produced in the West and Asia.

One carbon credit is equal to one tonne of carbon dioxide, or in some markets, carbon dioxide-equivalent gases.

The BBC reports that officials hope the trade in carbon credits will open up investment in the generation of renewable energy and forestry projects.

Kenya's government estimates that its largest forest, the Mau, has the potential to earn the country close to $2bn (£1.2bn) a year over the next 15 years.

Before the country runs to the bank, this value would have to be certified by the United Nations Framework Convention on Climate Change, the report added.