On Tuesday, a new US-trained Colombian anti-narcotics battalion becomes operational, heralding a new era of American involvement in the war against drugs.

The 1,000-strong battalion is the new face of the US war against drugs in Colombia, a war which until now the Americans have been losing as the flow of drugs to US shores increases and the amount of land under drug cultivation reaches record levels.

Trained by the crack US Green Berets and equipped with US helicopters, the new battalion is designed to take on Colombia's illegal armies, both leftist guerrillas and rightist paramilitaries.

They both protect drug fields and labs, and earn an estimated $600m a year from the drugs trade.

Outgunned

Until now, the drug war has been in the hands of special anti-drug police, but they are increasingly finding themselves heavily outgunned by the country's estimated 20,000 guerrillas and 5,000 paramilitaries and are unable to operate in the more than 40% of the country where these illegal armies hold sway.

US military aid to Colombia stands at over $280m a year and Colombia has requested that be increased to $500m a year, a petition that seems likely to be granted according to US sources.

The line between the war against drugs and the war against Marxist rebels has become blurred, according to the top US drug official, General Barry McCaffrey, who wants to see a steep increase in military aid to Colombia, but has ruled out direct intervention.