The United States military has completed its withdrawal from air base 201 in Niger, officials said on Monday, after Niger's ruling junta ordered nearly 1,000 U.S. military personnel to leave following a coup last year.

Air base 201, a drone base near Agadez in central Niger that was built at a cost of $100 million, had provided crucial intelligence about Islamist militant groups before the coup.

A joint statement from Niger's defence ministry and the U.S. military said personnel and equipment from the base had been withdrawn and coordination would continue over the coming weeks to make sure the pullout is complete.

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

Niger's junta has given the U.S. until Sept. 15 to remove troops from its territory. U.S. troops pulled out of air base 101 last month.

Niger's decision to ask for the removal of U.S. troops came after a meeting in Niamey in mid-March when senior U.S. officials raised concerns about issues such as the expected arrival of Russian forces and reports of Iran seeking raw materials in the country, including uranium.