Subsistence farmers: 'No alternative to coca'

But while the army claimed on Thursday that the programme has been an unqualified success, local farmers complain that legal crops have been destroyed along with the coca fields.

There are also concerns that spraying herbicide from helicopters is causing health problems, particularly among children.

And the army has not yet directed its eradication efforts on areas held by the country's powerful left-wing guerrillas, who oppose the plan.

Army deployed against drugs

Anti-drug fumigation began on 19 December, with 2,000 Colombian army personnel beginning the operation in the Putumayo region.

The region, on the southern border with Ecuador, is the country's coca-growing heartland.

Mr Pastrana has not secured EU aid

The US has contributed $1.3bn to Plan Colombia, a massive reform programme for the country that includes a renewed attack on drug trafficking.

Colombia produces two-thirds of the world's cocaine, according to US satellite data from 1999.

But Colombians who oppose the anti-drug programme say the US must control the demand for cocaine at home, rather than trying to destroy the source abroad.

The European Union has refused to back Plan Colombia, despite requests from President Andres Pastrana.

The Revolutionary Armed Forces of Colombia - known as the FARC - oppose US involvement in Colombia's anti-drug efforts.

The powerful left-wing guerrilla group also objects to aerial spraying, saying coca eradication should be done by hand.

And human rights groups say that because the programme does not offer subsistence farmers any alternative to growing coca, it will force them to clear virgin forest land to try to continue producing the crop.