By Jeremy McDermott BBC, Colombia

The government claims success for its get-tough policy

A report just released by the United Nations says that drug cultivation in Colombia has decreased - the result, the Colombian and US Governments say, of an unprecedented aerial eradication programme.

But there is evidence that drug crops are migrating to other countries in the region and that part of the fall may be due to a drop in demand for cocaine in the United States - the world's biggest drug market.

COLOMBIA'S COCA CROPS 144,807 hectares under cultivation in 2001 102,000 hectares under cultivation in 2002

The Colombian Government is heralding the UN report as evidence that its get-tough policy on drugs and massive aerial eradication programme, financed by the US, is working.

The UN report says that drug crops have fallen by some 29%, meaning the total cocaine production in Colombia had dropped from over 600 metric tons in 2001 to 480 tons last year.

But the Colombian figures do not tell the whole story.

Revenue drop

Firstly, there has been an increase in drug cultivation in neighbouring Bolivia and Peru, and crops have appeared for the first time in Ecuador.

In the coca-growing heartland of Colombia, the southern province of Putomayo, there was a massive drop in registered drug production.

But sources on the ground said peasants are now cultivating very small fields to avoid the attention of the spraying aircraft, and many of these are too small to appear on the satellite imagery the UN based its report on.

Another reason for the drop in cultivation may also be due to the fact that the US market - the world's biggest - is experiencing a rise in popularity of synthetic drugs over cocaine and heroin supplied by Colombia.

What is certain is that the drop in drug crops will hit the revenue of Colombia's warring factions that earn most of their money from illegal narcotics, and that can only help the Colombian Government in its battle to regain control of the 40% of the country the illegal armies control.