The United States military is planning to set up a base for drones in northwest Africa to bolster surveillance of al-Qaida's affiliates in the region and allied Islamist extremists, a US official said on Monday.

The base for the robotic, unmanned aircraft would likely be located in Niger, on the eastern border of Mali, where French forces are waging a campaign against al-Qaida in the Islamic Maghreb, known as AQIM, said the official, who spoke on condition of anonymity. The base was first reported by the New York Times on Monday.

The airfield would allow for better intelligence gathering by unarmed drones on the movement of AQIM and other militants, which Washington considers a growing threat, the official said.