The report, titled "The scars on 'Mother Earth,'" said the rebel groups' tactic of blowing up oil pipelines, had polluted the Andean nation's ecosystem with more than 2 million tonne of crude oil in the last decade.

The drug trade, it said, contaminated the soil with 200,000 tonne of chemicals a year, and causing deforestation at a pace that was rapidly destroying the country's jungles.

"Guerrillas and paramilitaries have caused this ecological catastrophe which, ... if the current rate of deforestation continues, will turn half the country's jungles into pasture in 17 years," the report said, quoting environment ministry experts. It said the heavily wooded regions of Amazonas, bordering Peru in the South, and Orinoquia, which borders Venezuela and Brazil in the east, were in "imminent danger."

Colombia is one of the world's five top countries in terms of water resources and biodiversity, the environment ministry says. No one there was available for comment on the report. The army calculated that about 3,600 square miles (9,300 square km) of jungle and agricultural land had been lost in the past decade.

Although a tiny proportion of Colombia's total area of about 441,000 square miles (1.1 million square km), the destruction still represents "ecological damage ... of unsuspected proportions," it said.

Colombia has been torn by four decades of strife - the longest conflict in Latin America - involving the leftist Revolutionary Armed Forces of Colombia (FARC) and the National Liberation Army (ELN), far-right paramilitary death squads and the army, which critics accuse of being linked to paramilitaries or turning a blind eye to their activities. The war has claimed 35,000 lives in the past decade alone.

The United States believes the 17,000-strong FARC, Latin America's biggest rebel army, plays a dominant role in drug production. Colombia is the source of 90 per cent of the world's cocaine, with annual output of 520 tonne, and it also produces 6 tonne of heroin annually, according to the US Drug Enforcement Agency.

Guerrillas have targeted oil, Colombia's main export, as a tactic in their war against the state, staging some 1,000 assaults on oil pipelines since 1986. The 5,000-strong ELN has been responsible for 80 per cent of the assaults.

The army report, citing environment ministry figures, said crude oil had contaminated 1,625 miles (2,600 km) of river, equivalent to the total length of Colombia's two biggest rivers, the Cauca and the Magdalena, with slicks of up to 112 miles (180 km) in length. The report called the drug trade "one of the direct causes of the destruction of biodiversity," saying coca leaf, poppies and marijuana cultivation had caused serious deforestation.

(Reuters)