Militants armed with heavy machine guns and rocket-propelled grenades stormed the army post in Washir district of Helmand province late Tuesday, sparking a fierce firefight lasting more than an hour.

"Unfortunately nine ANA (Afghan National Army) soldiers were killed and seven others injured in the fighting," provincial spokesman Daud Ahmadi told AFP. Seven Taliban were also killed, he said.

A group of Afghan policemen sent as reinforcements were ambushed on the way and five insurgents were wounded and captured, Ahmadi said.

The Taliban, toppled in late 2001 in a US-led invasion, are waging an insurgency against the government and US-led forces, who have some 130,000 troops in the impoverished and war-ravaged country.

But the international coalition will withdraw by the end of 2014, and Afghan forces, who are being trained to take over responsibility for security, are increasingly coming under attack.