Officials in northern Afghanistan say insurgents have killed 11 Afghan policemen and a district governor during attacks in the once-calm region.

Authorities said Sunday that at least six border police officers died late Saturday when Taliban militants stormed a police post in (the Imam Saheb district of) northern Kunduz province.

In a neighboring area of Kunduz, attackers used a remote-controlled bomb to kill the governor of the Qal'ah-e Zal district on Saturday.

In another northern province, Badakhshan, a roadside bomb struck an Afghan police patrol, killing five officers.    

Meanwhile, NATO says one of its soldiers died Sunday after an insurgent attack in southern Afghanistan.   

Six American soldiers were killed Saturday in bomb blasts and other attacks in southern and eastern Afghanistan.

In other reports Sunday, Afghan officials said a joint force of international and Afghan troops killed 13 Taliban during a raid in southern Zabul province Saturday.

NATO said a joint force killed several insurgents and detained two others Saturday while pursuing a Taliban commander affiliated with al-Qaida in eastern Ghazni province.

NATO also said a separate force of Afghan troops killed two insurgents during an operation targeting two Taliban commanders in southern Kandahar province.

Insurgent attacks have intensified across Afghanistan as international forces step up raids to root out Taliban militants.  Last month was the deadliest for foreign troops, with 102 deaths.

Some information for this report was provided by AP, AFP and Reuters.