The Ugandan government wants to change the law to allow Mabira Forest Reserve, the 30,000 hectare rainforest in Uganda which has been protected since 1932, to be carved up and a quarter of it used for sugar cane production by huge firms, notably the Mehta Group, which has close ties to politicians within and outside the country.

The forest is home to nearly one third of Uganda's bird life. Sugar cane is a notoriously un-economical crop.

The forest was supposed to be protected in return for $US 360 million of World Bank money to fund construction of a hydroelectric dam on the River Nile close to Lake Victoria.

Conservationists fear that agreement will be flouted and that Mabira will be all but destroyed by the planned give-away – or de-gazettement - after November’s Commonwealth Heads of Government Meeting in Uganda when the country will no longer be in the world’s gaze. They believe the move would breach the Ugandan constitution.

Dr Chris Magin, the RSPB’s International Officer for Africa, said: “Slicing up Mabira would be an environmental disaster and makes no economic sense at all. Sugar production in Uganda is hugely inefficient and has to be heavily subsidised to be competitive.

“Sugar yields would be much higher if farming techniques were improved and if the object was to increase sugar production, that is what the government should do.”

The 75,000-acre (30,000-hectare) Mabira forms the eastern part of the Guinea Congo Forest in central Africa. It is classified as an Important Bird Area by BirdLife International boasting almost 300 bird species including the globally threatened Nahan's francolin, which is similar to the partridge.

Of those birds, 75 species are found only in the Guinea Congo Forest. Many of the 200 tree species and nine primate species, for which Mabira is known, are also rare.

“For bird watchers and other eco-tourists, it is a famous site,” Dr Magin said. “It would be a tragedy if so much of it was lost to this short-sighted venture.”

A recent study by the conservation group NatureUganda highlighted Mabira’s economic importance to the country, particularly its carbon and water storage, and the provision of food, medicine and wood to local communities.

Mabira is the best source of food and materials for the people of the traditional Buganda Kingdom, which surrounds Mabira prompting the Kingdom to offer alternative land to Mehta.

Eco-tourism is now Uganda’s second largest foreign exchange earner with 62 per cent of income from visits to Uganda’s forest reserves coming from Mabira. The site lures thousands of tourists and students every year. It is just 20 miles from the Ugandan capital Kampala and this proximity, together with the construction of eco-lodges, means it could soon attract more tourists than any other Ugandan site.

“Mabira is a biodiversity heaven and conserving it is a much better option than growing sugar cane,” said Achilles Byaruhanga, Executive Director of NatureUganda.

“If a quarter of Mabira is chopped down the effect on the remaining forest will be far-reaching, reducing the range of species, causing encroachment, erosion and siltation, and reducing its capacity to provide services. There will be less water in our rivers, less rain, less carbon stored and fewer tourists.”

The Ugandan government and the EU have already funded recovery work in Mabira, after almost a century of logging damaged much of it. Mathias Kigongo, a district councillor for Naja sub-County – which is next to Mabira – says far more jobs would be lost than created by increasing sugar cane cultivation.

“We feel the forest should not be touched,” he said. “The benefits from sugar cane cannot be equivalent to what we would lose.” Mr Kigongo would like more land added to the forest to protect the watershed for Lake Victoria and the Nile.

The RSPB and BirdLife International are urging people to lobby their governments to ask Uganda to safeguard Mabira. Hazell Shokellu Thompson, Head of BirdLife’s Africa Division, said: “For the Ugandan government and the Mehta Group to continue with a venture that is so very costly in terms of biodiversity loss and economic stability is wholly deplorable.”

“Uganda ratified the Convention on Biological Diversity (CBD) in 1993 and has a fairly good track record in upholding that treaty. The government has an obligation to continue to adhere to the agreement in the same way that many other African and world nations are doing and we are confident that once all the facts have been reviewed, the Ugandan government will do the right thing for the Ugandan people and stop the give-away.”

If the Mabira give-away goes ahead, conservationists fear it will put other protected forests at risk. Dr Magin said: “Mabira is only one of a number of give-aways proposed. If the government is successful in weakening the law the loss of Mabira could set a very worrying precedent.”