NATO "cannot win" the fight against the Taliban alone and will have to train Afghan forces to do the job, the UN's top official in the country said on Friday.
"At the moment NATO has a very optimistic assessment and they think they can win the war," warned Tom Koenigs, the German diplomat heading the UN mission in Afghanistan. "They say development can follow military action. But there is no quick fix."
The military alliance "does not understand Afghan ownership" and should "stop doing things on their own," he said.
Training the fledgling Afghan National Army (ANA) to defeat the Taliban is crucial.
"They [the ANA] can win. But against an insurgency like that, international troops cannot win," he said.
Koenig's forthright comments in an interview highlight divisions between key international partners as NATO -- which recently assumed military control of the entire country -- battles to quell a swelling insurgency.
He was speaking as British Prime Minister Tony Blair prepared to fly to Pakistan for talks with Pakistani President Pervez Musharraf, who is becoming a key figure in the fight against the Taliban and its allies crisscrossing the border into Afghanistan.
In an interview with al-Jazeera on Friday, Blair came the closest so far to admitting that the invasion of Iraq had been disastrous. Challenged by journalist Sir David Frost, who said that the western intervention in Iraq had "so far been pretty much of a disaster," he responded: "It has, but you see what I say to people is why is it difficult in Iraq? It's not difficult because of some accident in planning, it's difficult because there's a deliberate strategy -- al-Qaeda with Sunni insurgents on one hand, Iranian-backed elements with Shiite militias on the other -- to create a situation in which the will of the majority for peace is displaced by the will of the minority for war."
British commanders have argued that UK troops should be withdrawn from Iraq to allow the military to focus its efforts on stabilizing Afghanistan.
But NATO commanders on the ground have been pleading for an extra 2,000 troops, more helicopters and armored vehicles to little effect. On Friday night NATO Secretary-General Jaap de Hoop Scheffer said that caveats imposed by countries on what their troops can do should be lifted.
"My strong plea to governments would be: Please help us in lifting those caveats as much as possible ... because really in Afghanistan it is a problem," he said.
British Secretary of State for Defense Des Browne made clear on Friday that the future of the alliance was now bound up with the future of Afghanistan.
"The Afghan people, our own people and the Taliban are watching us. If we are indecisive or divided, the Taliban will be strengthened just as all of the others despair," he said.
Attacks have increased fourfold this year and 3,700 people have died, mostly in the volatile southern Afghan provinces. The US Air Force has carried out 2,000 air strikes in Afghanistan since June compared with 88 in Iraq.
Last week Acbar, an umbrella group of Afghan and international aid agencies, said the crisis highlighted the "urgent need" for a rethink of military, poverty-reduction and state-building policies.