The five experts, from the US, Japan and France, plan to siphon off carbon dioxide from lakes Nyos and Monoun, which are about 375 miles from the capital, Yaounde.

The noxious cloud also killed fauna and flora

In August 1986, a disturbance underneath Lake Nyos caused a cloud of toxic gas trapped underneath the water to shoot to the surface, killing 1,800 people and thousands of animals in nearby villages.

A similar phenomenon had occurred in Lake Monoun, about 60 miles south of Nyos, two years earlier. That eruption killed 34 people.

In 1992, the Cameroon Government made a trial attempt to siphon off the gas. It appeared to be successful, but was abandoned for financial reasons.

This time, the government is being helped by $450,000 donated by the US in September.

Since March, the plan has become more urgent, as volcanic activity caused Mount Cameroon to erupt for the first time since 1982.

This triggered a build-up of carbon dioxide under the two lakes, which is threatening further danger.

Flooding threat

"There is more gas in the two lakes than (from) previous explosions. The earlier the gas is removed the better," Professor George W Kling from the University of Michigan told a Yaounde workshop on Tuesday.

Professor Michel Halbwachs from France said the plan was to use a single tube to siphon off the gas gradually, so that the gas dispersed naturally, in a safe, controlled manner.

Professor Minoru Kusakabe from Japan said that within five years, half of Lake Nyos's carbon dioxide would have been removed and 80% of Monoun's gas would have gone.

But the plans to pump off the gas are not without danger.

One of the problems is that the lakes have comparatively fragile walls, which if breached by changes in pressure during the operation could cause a huge flood in the towns nearby.