On patrol with British troops in Helmand | Video: Afghan soldiers battle the Taleban

Four British soldiers in Afghanistan, including the first woman to die in action there, were killed after their vehicle was struck by a roadside mine during a secret anti-terrorism mission, Times Online has learnt.

The female soldier, a member of the Intelligence Corps, was on the mission with three SAS reservists. It was the greatest single loss of life for the Territorial Army since the Second World War and means that nine British soldiers were killed in Afghanistan in nine days.

The reservists from the 23rd Special Air Service Regiment were providing support for an operation by the Afghan National Police on Tuesday afternoon.

Their Land Rovers were caught by a roadside bomb or mine at 3.40pm local time yesterday east of Lashkar Gah, the headquarters of 16 Air Assault Brigade, in Helmand Province.

Three of the soldiers were killed in the blast and another was pronounced dead on arrival at Camp Bastion. A fifth soldier wounded in the attack is being treated for his injuries and is said to be in a stable condition.

Soon after news of the deaths was announced, it emerged that two more Nato soldiers were killed today and 10 wounded while out on patrol in Paktika province in eastern Afghanistan. Their nationality has not yet been confirmed, though most of the troops in the area are American.

The dead female soldier, a member of the Intelligence Corps, is the first British servicewoman to die on active service in Afghanistan, although women troops have been killed in Iraq.

Defence sources have confirmed that the other three dead were Special Forces reservists from the 23rd Special Air Service Regiment, which is one of two Territorial Army SAS units.

Next of kin have been informed and the names of the dead will be released after a 24 hour period for private grief.

The deaths represent the biggest single loss of life for British forces in Afghanistan since September 2006, when 14 personnel were killed when an RAF Nimrod came down near Kandahar.

They take the number of British service personnel who have died since the start of operations in November 2001 to 106, 80 of them killed in action. In a grim fortnight for British forces, five soldiers from 2 Para, based in Colchester, Essex, were killed in two separate incidents in Afghanistan last week.

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