War planes attacked and killed 22 Taliban militants in southern Afghanistan's Helmand province, where a British soldier was also killed in a bomb blast, officials said Friday.

An insurgency led by the extremist Taliban militia is particularly active in Helmand, also the main producer of Afghanistan's substantial opium crop from which the militants earn money, AFP reported.

Around 30 insurgents had gathered outside the provincial capital Lashkar Gah late Thursday to attack the town, provincial police chief Asadullah Shirzad told AFP.

However, authorities had learnt of the plan and called the NATO-led force to send in aircraft which bombed them before they could enter, he said.

"Twenty-two Taliban were killed and six of them were known commanders," he said.

Afghan security forces had moved into the area afterwards and seen some of the bodies and weapons on the ground, he said.

NATO's International Security Assistance Force (ISAF) could not immediately confirm the operation.

The British defence ministry announced meanwhile that a British soldier was killed in Helmand on Thursday in a bomb blast.

The royal marine, who has not been identified, was in a vehicle near Lashkar Gah when the explosion occurred, the ministry said.

The Taliban were in government between 1996 and 2001 and are battling Afghan and international forces to take back power.

The insurgency is most active in southern Afghanistan where the United States has started to deploy most of the 21,000 reinforcements due this year.