Six policemen with the Afghan Border Police Force were killed as militants stormed their outpost Saturday night in Imam Sahib district of Afghanistan's northern Kunduz province, Mohammad Ayub Haqyar, governor of Imam Sahib district said on Sunday.

"Armed militants stormed an outpost of border police in Satar Perhi area of Imam Sahib District Saturday night. As a result six police personnel were killed," Haqyar told Xinhua.

An investigation has been initiated to probe into the incident, he said.

Imam Sahib district is located in the northern part of Kunduz bordering Tajikistan.

Meantime, a Taliban purported spokesman Zabihullah Mujahid, in talks with media via cell phone form an undisclosed location, claimed responsibility for the attack and said that they have stormed the police and killed nine policemen there.

The hard-liner militias have vowed to speed up their assaults against the government and NATO-led forces this year in the war- torn central Asian state.

A roadside bomb organized by militants also killed the district chief of the neighboring Qalai Zal district in Kunduz province on the same day Saturday.

Kunduz and neighboring Baghlan province have been the scene of spiraling Taliban-led militancy since early this year.