By Jeremy McDermott BBC correspondent in Bogota

The top human rights official in Colombia has urged the government to suspend the US-backed aerial fumigation of illegal coca crops in the south of the country.

Opponents say spraying damages health and the environment

The Colombian state's human rights watchdog, the People's Defender, accused the authorities of damaging the health of locals and the environment in the province of Putumayo.

Every year the American Government finances the aerial fumigation of more fields of coca and poppy, the raw materials for cocaine and heroin, and every year the number of hectares under drug cultivation goes up, along with the amount of virgin forest destroyed.

Yet this year, with the blessing of hardline President Alvaro Uribe, more hectares than ever will be fumigated.

Peasant victims

The policy has long been criticised by human rights groups and environmentalists.

Uribe is a champion of the US-backed programme

Human rights groups say the policy attacks the weakest part of the drugs chain - the peasant farmers who grow coca as the only way to survive and do not share in the massive profits that the smugglers and dealers in the US get.

Environmentalists complain that the herbicides used damage the environment, killing all plant life, not just drug crops.

And now the People's Defender's office has weighed in, calling for a halt to spraying in Putumayo, Colombia's coca growing heartland.

Eduardo Cifuentes, the Colombian ombudsman, said he has received more than 6,500 complaints this year of planes fumigating food crops, leaving peasants without a livelihood, damaging the health of people - particularly children caught outside as the chemicals are dropped - and causing great damage to the sensitive eco-system of the Amazon.

No notice

But the government is unlikely to pay the slightest attention to the latest protest.

President Uribe has vowed to eradicate drugs altogether from Colombia as part of his war to re-establish state authority.

Plus the fact the US insists the policy must continue.

And since Colombia is one of the top recipients of US aid in the world, it is unlikely to risk offending its powerful northern neighbour.