Residents say fighters linked to the Islamic State group have seized an ancient port town in Somalia's semiautonomous northeastern state of Puntland.

Hassan Adan, an elder in Qandala, said up to 50 armed militants captured the town Wednesday after security forces withdrew. The town is 75 kilometres (47 miles) east of Puntland's commercial hub, Bossaso.

Adan says the attackers raised their black banner in the town.

The development marks the first victory for the fighters, who are expanding the areas under their control amid a rivalry with the al-Shabab extremist group.

The fighters broke away from al-Shabab and declared allegiance to the Islamic State group last year.

Al-Shabab sees the splinter group as a threat to its operations in the Horn of Africa nation.