Tom Coghlan in Kabul

British and Afghan forces repulsed an attempt by hundreds of Taleban fighters to attack the provincial capital of Helmand, Lashkar Gah, on Saturday night in the most audacious Taliban attack in the province since 2006.

Up to 100 Taleban fighters were killed in a series of airstrikes and firefights around the city outskirts in fighting that began in the early evening as Taleban fighters were concentrating to attack the city of three sides and continued into the early hours of Sunday morning.

It was the first time that the Helmand capital has been attacked.

The Taleban plan appeared to be for a "Tet Offensive" style infiltration of the city, the seat of the Afghan provincial government and home to the headquarters of the British commander in Helmand and the civilian reconstruction component of the British mission in Helmand.

Had the infiltration succeeded then British and Afghan forces would have faced confused street fighting in which Western airstrikes would have been impossible without the risk of causing mass civilian deaths in the city.

A British army spokesman said that the Taleban operation displayed "a level of co-ordination that wasn't expected." He estimated the Taleban forces at around 170, though some Afghan estimates were much higher.

However, British officials insisted that there was absolutely no threat of the British base falling. "Whatever their military objectives were, we didn't get to find them out, because they were defeated on the edge of the city" said the Helmand Task Force spokesman Lieutenant-Colonel Woody Page.

"At around 1700hours we detected terrorist vehicles moving in just to the west of the river (on the western edge of Lashkar Gah). By 1730 there were three or four separate groupings. There appeared to be a plan to attack on three different sides, with a blocking force on the fourth side. We waited until the terrorists were concentrated and then attacked with maximum effect," he added.