A bomb disposal squad from the Japanese army was investigating Wednesday an explosion at Miyazaki Airport in the country's southwest, local media reported.
The airport's runway was closed following the explosion on a taxiway, although no injuries were reported, according to Kyodo News.
The explosion is suspected to have been caused by unexploded U.S. ordnance from World War II, which is frequently discovered in the area.
All flights to and from Miyazaki Airport were suspended as a result of the explosion and subsequent runway closure.
Officials discovered a hole on the taxiway measuring 7 meters (23 feet) in diameter and 1 meter (3 feet) deep, the report said.
