Economists in Malawi, one of Africa's poorest countries and biggest grower of burley tobacco, said Sunday there was "cause for huge concern" after 172 countries agreed on guidelines to control the use and sale of tobacco products.

Thomas Munthali, one of Malawi's leading economists, said the country should fight to stop the immediate implementation of the tobacco controls, saying it would be "disastrous" for its fragile economy which is also supported by donors.

He said diversification from tobacco in Malawi "cannot happen overnight".

"There is cause for huge concern because Malawi has not diversified its economy to allow for tea and sugar industries to grow", Clement Thinda, chief executive officer of the Tea Association of Malawi, told AFP.

Thindwa said both tea and sugar industries -- which are at par as the second foreign exchange earners after tobacco -- had failed to expand because of the shortage of land.

"We have been fighting to expand, but we are limited because of land," he said.

Malawi is not party to the World Health Organisation (WHO) Framework Convention on Tobacco Control (FCTC) and cannot access its support for tobacco alternatives.

On Saturday the WHO meeting in Uruguay, known as the fourth meeting of the Conference of the Parties (COP) to the global tobacco treaty, approved guidelines on controlling tobacco flavorings and additives despite lobbying from the tobacco industry.

Malawi is the world's biggest producer of burely tobacco, which is grown by some 300,000 peasant farmers, resulting in the world's most tobacco-based economy, a study by the International Growers Association shows.

Tobacco, called "green gold" in Malawi, contributes 30 percent to the agriculture-powered economy and 25 percent to government revenue. Some 500,000 people are employed in the sector.