The British Government said destroying poppy fields remained a key deterrent to growers and one of the "seven pillars" of its anti-opium strategy in Helmand province, just a day after Richard Holbrooke, the US envoy to Afghanistan, said that destroying the crop only drove poor farmers to join the insurgency.
In a reversal of policy, he said the United States would stop funding poppy eradication and instead concentrate on encouraging farmers to grow alternative crops.
The Afghan government backed Britain's stance and defended its previous efforts, which relied heavily on ripping up or flattening poppy plants, as "perfect".
General Khodaidad, Afghan minister for counter narcotics, said his strategy had been "the right path".
"We are happy with our strategy and we are working according to our strategy. I don't see any deficiencies in our strategy, our strategy is perfect, our strategy is good."
Mr Holbrooke's reversal is the latest change in policy as the US struggles to stem a growing Taliban-led insurgency.
Ten thousand US troops have arrived in Helmand this month with commanders admitting overstretched British troops are at a "stalemate".
International governments have repeatedly disagreed on how to tackle Afghanistan's rampant opium business which supplies more than 90 per cent of the world's heroin and feeds hundreds of millions of dollars to insurgent fighters.
Britain and other Nato allies strongly opposed former US plans to destroy poppies with crop-spraying planes saying it would only strengthen the increasing insurgency.
Mr Holbrooke, speaking at a Group of Eight summit dedicated to Afghanistan, said he now felt eradication was "a waste of money". He said it "might destroy some acreage, but it didn't reduce the amount of money the Taliban got by one dollar".
He added: "The farmers are not our enemy, they're just growing a crop to make a living. It's the drug system. So the US policy was driving people into the hands of the Taliban."
Britain leads international reconstruction efforts in Helmand province, where 60 per cent of the Afghan opium crop is produced.
The British government is spending more than £290 million on a three-year-programme of eradication, support for farmers and pursuit of drug barons and traffickers.
British officials denied there was tension with the US over the policy change and said the detail had not been decided.
A spokeswoman at the Department for International Development said: "Eradication is a key part because of the deterrent effect, not because we are going to destroy the whole crop." She said eradication targeted big growers rather than poverty-stricken small farmers.