Al-Qaeda is seeking increasingly to join the fight against Nato troops in Afghanistan while younger, more ruthless leaders are rising within the ranks of the Taleban, the commanding general of the alliance has claimed.

General Dan McNeill said there was evidence that young, radical Afghan guerrillas, some influenced by al-Qaeda, were moving into gaps in the leadership left by the deaths of commanders who may have shown restraint by trying to avoid civilian deaths.

Speaking to The Times in Kabul, the general said that in the past year Nato had succeeded tactically on the battlefield and against the enemy's command and control structure — a military euphemism for killing commanders. He said: “There are sanctuaries just out of reach of the security forces and those sanctuaries breed radicalised people, so you would expect that no matter what happens on the battlefield there will be repopulation of the enemy. Can they replace leaders who learnt their trade fighting against the Soviets, and who were very good at it? The younger leaders are a lot more radicalised, but maybe not as effective on the battlefield. These types will try asymmetrical tactics — we are likely to see more IEDs [improvised explosive devices] and more suicide bombers.” Insurgents could alienate the population, he said, by killing innocent Afghans in bomb attacks.

Intelligence reports suggested that al-Qaeda was again active in the east of Afghanistan, along the Pakistan border, and to a lesser extent in the south, where 7,800 British troops are based, mainly in Helmand province.

“I would expect that al-Qaeda would be more involved in Afghanistan,” General McNeil said. “They have had tremendous pressure in other conflict areas — specifically Iraq — and they read the newspapers and know the debate among policymakers. There is an implication that we don't have this place covered.”

Since al-Qaeda was forced out in 2001 there has been little evidence of involvement in Afghanistan, where it has been traditionally disliked, even by many Taleban, because of its fanaticism.

The Afghan insurgency was made up of four or five different groups, including the Taleban, some of whom had fought each other in the past, he said, adding that large numbers of Nato forces would be needed until around 2012, when Afghan security forces would be ready to take over.

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