The Afghan President, Hamid Karzai, is resisting American pressure to authorise a major programme of crop spraying to eradicate the country's massive opium crop amid warnings that it would lead to a rise in support for the Taliban. The plan has been strongly opposed by the British, who hold that it will make the task of the military in Helmand, the province which produces 50 per cent of the opium crop, much harder. Spraying from the air, critics say, carries with it the danger of destroying other crops, causing long-term ecological damage, and affecting the health of livestock.

But according to senior Western and Afghan officials, the American position has been significantly strengthened following the latest poppy harvest, which shows a jump of 34 per cent from last year, which was already a world record. America's determination has also been sharpened with the evidence that Afghan opium, which now accounts for 93 per cent of the world's supply, has started reaching markets in the United States.

The recent appointment of a former US ambassador to Colombia as envoy to Kabul is seen as the most overt move by Washington to ensure that spraying takes place in Afghanistan. William Wood, who has acquired the nickname "Chemical Bill" among British and other Nato officials for his fervent belief in chemical spraying, was in the team which implemented "Plan Colombia", which involved aerial spraying in the Latin American state in an attempt to eliminate cocaine production.

The policy in Colombia came under severe criticism with claims that it damaged legitimate crops and ultimately failed in its aims of destroying the coca crop. However, during his confirmation hearing before Congress, Mr Wood said the Colombian option may be repeated in Afghanistan and General Peter Pace, chairman of the US joint chiefs of staff, has also voiced the opinion that it could be a template for Afghanistan. Members of the Colombian security forces are already training Afghan police in counter-narcotics.

A recent meeting of the Afghan cabinet, according to senior officials, came close to approving the use of spraying on a limited, experimental basis. However President Karzai is said to have agreed to delay the decision after impassioned pleas from the ministers of Agriculture and Public Health. The issue remains immensely sensitive and yesterday President Karzai's spokesman insisted: "Our view is there should be a comprehensive policy to tackle the problem, including the provision of alternative livelihoods. It was decided that we will not start crop spraying. This was a unanimous decision by the government."

Yet Ahmed Zia Massoud, one of Afghanistan's two vice-presidents, has publicly declared his support for spraying. He said: "I have no doubt that the efforts of Britain and the international community in fighting the opium trade in Afghanistan are well-intentioned, and we are grateful for their support. But that policy has not worked and the time has come for us to adopt a more forceful approach.

"We must switch from ground-based eradication to aerial spraying. The opium directly supports those who are killing Afghan and international troops. Failure to achieve a substantial reduction in the opium crop will be equivalent to supporting the Taliban."

A US diplomatic source said: "There is absolutely no evidence that spraying causes harm to people or cattle. Everyone has seen the rise in the poppy harvest, and obviously the current policy is not working."

(By Kim Sengupta and Ahmed Nasruddin Ali, The Independent, 04/10/2007)