File photo: CGTN

TOKYO, Nov. 8 (Xinhua) -- Japanese Defense Minister Taro Kono on Friday apologized for not immediately notifying the governor of Aomori Prefecture, northern Japan, of a U.S. fighter jet accidentally dropping an inert bomb on private land in the prefecture earlier in the week.

Following the incident, which occurred north of the Misawa Air Base at around 6:30 p.m. local time on Wednesday, Kono apologized to Aomori Gov. Shingo Mimura for the delayed notification, stating that the bomb "was very heavy, so it could have caused a major accident."

Mimura, for his part, however, expressed his concern and dissatisfaction over the delay in receiving the information from the defense ministry and told Kono to ensure measures are put in place to avoid a recurrence of the military mishap.

"It will cause great concern among people in the prefecture and amplify distrust of the safety management of U.S. forces," Mimura said.

On Thursday, a day after the incident, the defense ministry said a U.S. F-16 fighter jet had accidentally dropped a dummy bomb weighing over 200 kilograms on private land outside of a designated target range in Aomori Prefecture.

Japan's top government spokesperson, Chief Cabinet Secretary Yoshihide Suga, said such incidents must not happen and that the U.S. side will be urged to prevent similar incidents from happening again. He added that an on-site investigation was underway.

The defense ministry lodged a protest with the U.S. military over the incident, which according to the U.S. side did not result in injury or damage.

Bombing drills by U.S. aircraft stationed at the Misawa base have temporarily been suspended, the U.S. Forces said.

In a prior Tweet on the matter, the U.S. Forces admitted that an "F-16 at Misawa released a device five kilometers from the Draughon range late Wednesday."

They notified the Japanese government on Thursday morning and saying an investigation into the cause of the incident was underway.

The Aomori prefectural government said the 200 kg object was found about five km west of the bombing range on private land.

The Draughon range, administered by the U.S., according to the defense ministry here, is the only area on the Japan's main island of Honshu where air-to-ground firing and bombing is allowed to be conducted.