But growers angry at the loss of their income have written to President Bill Clinton to demand compensation.

The BBC's Malcolm Brabant: "Troops are concerned about facing booby traps"

Caribbean troops, backed by American marines, will spend two weeks destroying the lucrative drug crop.

The plantations around the island's Soufriere Hills are said to yield some of the world's finest marijuana, and are normally fiercely protected by armed guards.

Sir James fears farmers may switch from bananas to drugs

Soldiers are worried they could encounter booby-traps as they leap from the helicopters.

There have been similar operations in nearby Trinidad, St Kitts, St Lucia, Dominica and Antigua.

But none has sparked the organised protest seen in St Vincent.

The Marijuana Farmers organisation has even sent a letter demanding compensation from President Clinton, who once famously puffed on a cannabis joint but never inhaled.

"There is a significant portion of our people who detest your intrusion and demand compensation for your action," the group wrote.

Its president, Junior Cottle, said the livelihood of 8,000 of the islands' 119,000 inhabitants depended on marijuana which was a "political stabiliser".

"To take this out of our economy overnight would bring hardship and endless misery on our people," he added.

Farmers warn of unrest

Without their plants, the farmers say unemployment in St Vincent and the Grenadines will rise above today's 40%.

That, coupled with US action against the Caribbean's banana industry, could provoke unrest on the island chain, they warn.

The US recently challenged a European Union quota system crucial to the region's banana industry which employs up to 60% of the workforce in St Vincent.

Prime Minister Sir James Mitchell has warned that without a European market for their bananas, many farmers will turn to growing and smuggling drugs.

With an estimated 5,000 hectares in production, St Vincent is the eastern Caribbean's largest marijuana producer.

Since 1994, police have destroyed more than 8.2 million plants on the island.

Much of St Vincent's marijuana is exported to other Caribbean islands.

Officials from the American Drug Enforcement Administration say the profits are often used to buy cocaine from nearby South America.

During the operation six US Marine Corps helicopters will ferry more than 120 troops from the Caribbean Regional Security Service and St Vincent police force to uproot and burn marijuana plots.

But many farmers said they planned to harvest their plants before the helicopters arrive.