Yumgan district in the northeastern province of Badakhshan fell to the Taliban following hours of clashes with security forces that raged after midnight on Saturday, the Badakhshan provincial council confirmed.
The district was under Taliban influence for four years before coming under government forces' control last September.
Sources within security institutions in Badakhshan said roads to the district have been closed, adding that there is a need for air support to the forces on the ground.
Meanwhile, clashes have been reported between government forces and the Taliban on the outskirts of Kunduz city in the north of Afghanistan.
The fighting started at around 10:30 am when a group of Taliban fighters attacked an army outpost near Pul-e-Safid village, Kunduz police spokesman Hijratullah Akbari said.
Akbari said no one has been harmed in the attack, so far.