Uganda will plant millions of trees in the next four years at a cost of $253 million, as it tries to restore dwindling forest cover to 30 per cent of its area from 22 per cent, the government announced.

Like many African countries, Uganda suffers from rampant deforestation that dries up rivers, triggers soil erosion and threatens wildlife, especially birds and primates.

But officials in the east African country also want the massive tree planting exercise to establish a recognised carbon sink that would enable it to earn credits on mechanisms set up to help countries meet their CO2 emissions targets.

Looking after forests, which suck carbon from the air, is seen as key in the battle against climate change, though the picture is complicated by a scientific study last year that showed living trees emit methane, a powerful greenhouse gas.

"Our aim is to plant trees in our forest reserves but also to encourage those who own private land to plant," said Moses Watasa, spokesman of the National Forest Authority.

"In four years, we think we should reach 30 per cent cover," he said.

Several local and international timber companies would be involved, though Mr Watasa declined to name any.

Much of the initial funding would come from donors.

The government has come under fire from environmental campaigners and donors this year for plans, strongly supported by President Yoweri Museveni, to give away rainforests to be destroyed and turned into plantations.

In May, the government rejected two unpopular proposals to turn over rainforest reserves to sugar and palm oil planters after violent protests in which at least three people were killed.

But the Environment Ministry says some 55,000 hectares of forest cover disappears in Uganda every year because of poverty and population pressure.

Many poor Ugandans in rural areas cut trees for firewood or timber.

"We are going to deploy forest rangers to tighten things up," Mr Watasa said.

Scientists say Uganda's robust terrain can regenerate forests quickly, owing to a combination of its favourably wet climate and fertile soils beefed up by occasional splashes of ash from volcanoes, past and present.