The Taleban have staged two of their most spectacular operations in Afghanistan, killing ten French troops in a battle just outside Kabul and launching a frontal assault on a big US base near the Pakistani border.

The attacks, which began on Monday and continued yesterday, are the latest in a series of dramatic raids by the militant group, including a prison break in Kandahar and the bombing of the Indian Embassy in Kabul, suggesting a tactical shift from multiple skirmishes to bold offensives.

They have also raised fears that the Taleban are expanding their operations in eastern Afghanistan as part of a new strategy to cut off supply routes to Kabul, the capital.

The attack on the French, of whom 21 were also injured, was one of the deadliest on foreign troops in Afghanistan since the start of the US-led war in 2001, which originally ousted the Taleban from Kabul. It was the heaviest loss of life suffered by the French since 1983 and increased pressure on President Sarkozy to withdraw from Afghanistan.

“In its struggle against terrorism, France has just been hit hard,” Mr Sarkozy said, before boarding an aircraft to Afghanistan to show support for his troops.

The French soldiers were on patrol with the Afghan National Army 30 miles (50km) east of Kabul when they were ambushed by about a hundred insurgents, sparking a gunfight that continued into yesterday, according to military officials. France has 2,600 soldiers in Afghanistan, mostly as part of the Nato International Security Assistance Force (Isaf), and has lost 24 in action or accidents since sending them there in 2002.

Mr Sarkozy dispatched an extra 700 soldiers after a Nato summit in April, when Washington asked allies to contribute more troops. Critics accused him of leading France into a Vietnam-style quagmire to regain favour with the Bush Administration.

The French are mostly deployed in Kabul province and Kapisa province, northeast of the capital, which is dominated by conservative Pashtun tribes.

Kapisa is also considered a stronghold of Gulbuddin Hekmatyar, a former Mujahidin leader who is now fighting Nato forces and is wanted as a terrorist by the US. The French were ambushed in Sarobi district, which is on the main eastern supply route between Kabul and Pakistan and is dominated by Pashtun tribes considered loyal to Mr Hekmatyar. Senior Taleban commanders told The Times this year that they aimed to cut off supply routes to Kabul. Since then the Taleban have closed in on the capital to such an extent that it is now dangerous for troops, aid workers and civilians to travel on the routes to the south, east and west of the city.

Haroun Mir, of the Afghanistan Centre for Research and Policy Studies, said that the Taleban appeared to be using the same tactics as the Mujahidin against Soviet forces.

Zabihullah Mujahid, a Taleban spokesman, declined to explain the aims of the Sarobi attack, but said that the French had lost 30 troops.

“Many civilians were killed when the French called in an airstrike,” he told The Times, without giving further details.

The Taleban also carried out two bold attacks over the past two days on Camp Salerno in the eastern province of Khowst, 20 miles from the Pakistani border, according to Isaf and Mr Mujahid.

Several car bombs on the base perimeter killed ten Afghans and wounded thirteen on Monday. Seven insurgents, including six suicide bomb-ers, were killed trying to attack the base yesterday, Isaf said. Mr Mujahid said that 30 insurgents took part and had killed 40 US soldiers, but Isaf said that no Americans had died.

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