Fighters pledging loyalty to the Islamic State (IS) extremist group have reportedly overrun new areas in the eastern province of Nangarhar.
The movement by the IS militants has caused many people to flee their homes, Radio Free Afghanistan reports.
There has reportedly been no military action taken against the IS group in Nangarhar, which borders Kabul Province and is not far from the capital city.
The reported advance by IS forces comes just days after the commander of U.S. and NATO forces in Afghanistan, John Campbell, said "foreign fighters" from Syria and Iraq had joined with militants in Afghanistan loyal to the IS group and were trying to establish a regional base in Nangarhar.
Afghan officials say they are also trying to track down broadcasts made by a pro-IS radio station, The Voice Of The Caliphate, that have been heard in the region recently.