Islamic State militants in eastern Afghanistan have taken to the airwaves to win recruits as they try to build strength and replace the Taliban as the leading force in the Islamist insurgency, Reuters reports.

Officials have been increasingly concerned by the broadcasts, which encourage young people to find a sense of direction in the radical movement.

If the broadcasts take hold, officials fear they will feed off a growing sense of hopelessness among many inured to war and struggling to get by in an increasingly tough economic climate.

"Most of our people are jobless and this radio will encourage lots of people to join their ranks," said Ahmad Ali Hazrat, head of the provincial council in Nangarhar.

"Now Daesh are seven kilometers outside Jalalabad city and if the government doesn't act soon it will expand its broadcast and recruit even from Kabul," he said, using the term widely used for Islamic State.

The 90-minute daily Pashto language broadcast, called "Voice of the Caliphate", consists mainly of interviews, messages and songs about Islamic State.

Officials in Nangarhar say they had so far been unable to block the broadcasts, which appear to shift location regularly.