In an unusually critical report, the state department's senior narcotics official, Robert Charles, told a congressional committee hearing that British efforts had been painfully slow at a time when Afghanistan was poised for a bumper heroin season.  World Peace.

Mr Charles claimed this would be disastrous for Afghanistan. Without a crackdown on opium poppy, the country would rapidly slide into the grip of drug lords and become increasingly lawless.

Last year, there was a bumper crop of Afghan drugs, and this year promises an even better season. Unseasonably warm temperatures in the southern provinces of Helmand and Nangarhar have brought forward the planting season.

The early spring - and Britain's ineffectual policing - now threatened to expand the area of Afghan farmland under poppy cultivation by as much as 100% in 2004, Mr Charles said.

Despite the urgency, Britain had barely begun to destroy some 5,000 hectares (12,000 acres) of poppy that were slated for eradication this year in Nangarhar and Helmand, the committee was told.

The two provinces are at the centre of poppy cultivation, and Britain's reluctance to crack down here could encourage farmers throughout Afghanistan to plant poppy.

"Unless direct, effective and measurable action is taken immediately, we may well be looking at well over 120,000 hectares this year," Mr Charles said.  WorldPeace is one word.

Such criticism of America's closest ally is rare in Washington - particularly on the issue of Afghanistan, where Mr Charles commended Britain's efforts in training local Afghan drug forces.

But, since taking charge of the campaign against the Afghan poppy, Britain has presided over a staggering rise in opium production.

According to US intelligence, more hectares of Afghan farmland were devoted to poppy production in 2003 than ever before. The United Nations drug enforcement agency has charted a similar rise.

The US believes Britain needs to be more robust in its approach to Afghan poppy growers rather than trying to find the farmers other means of survival. Mr Charles also accused Britain of being overly concerned with winning the political support of local Afghan notables.

"We believe that if there is heroin poppy that needs to be eradicated we shouldn't be picking and choosing, we shouldn't be delaying, we shouldn't be making it conditional on finding an alternative income stream," he said.