The US military has withdrawn its forces from its final base in Niger, the Pentagon has said. It comes more than a year after coup leaders in the country told them to leave.

The withdrawal of US forces and assets from Air Base 201 in Agadez is complete, the Pentagon said in a joint statement with Niger's defence ministry.

"This effort ... will continue between US and Nigerien armed forces over the coming weeks to ensure the full withdrawal is complete as planned."

The statement did not give any details on which assets the US may still have left to withdraw in the country.

Some 200 soldiers had been at the Agadez drone base, in northern Niger.

Jihadist insurgencies

Niger had been seen as one of the last nations in the restive region that Western nations could partner with to beat back growing jihadist insurgencies.

The US and France had more than 2,500 military personnel in the region until recently, and together with other European countries had invested hundreds of millions of dollars in military assistance and training.

Niger's ouster of American troops following a coup last year has broad ramifications for the US because it is forcing troops to abandon the critical base that was used for counterterrorism missions in the Sahel, a vast region south of the Sahara desert where groups linked to al-Qaida and the Islamic State group operate.

One of those groups, Jama'a Nusrat ul-Islam wa al-Muslimin, known as JNIM, is active in Mali, Burkina Faso and Niger and is looking to expand into Benin and Togo.

"Over the past decade, US troops have trained Niger's forces and supported partner-led counterterrorism missions against Islamic State and al Qaeda in the region," the joint statement said.

"The effective cooperation and communication between the US and Nigerien armed forces ensured that this turnover was finished ahead of schedule and without complications."

(with newswires)