Municipalities near an air base in Tokyo on Sunday asked for more evidence that flights of CV-22 Osprey aircraft are safe.

The US Air Force on Friday said the tilt-rotor transport aircraft was ready to fly again. Safety concerns caused them to be grounded last month.

Pilots at Yokota Air Base in Tokyo are scheduled to resume normal operations of CV-22 Ospreys on Wednesday after test flights.

A liaison body between the Tokyo Metropolitan Government and municipalities near the base submitted the request for more information to US forces and the Japanese Defense and Foreign ministries on Sunday.

The body said concerns about the safety of residents near the base would increase because of the planned resumption of CV-22 Osprey flights.

Japan's Defense Ministry and the US Defense Department are believed to have held talks on the matter.

Japanese defense officials reportedly said Japan and the US had established a procedure to safely operate CV-22 Ospreys without serious difficulties. They decided the aircraft no longer has issues that warrant blanket grounding.