The governor of the southern Japanese prefecture of Okinawa says he will continue asking local police to quickly share information about suspected sex crimes involving US military personnel.

Governor Tamaki Denny spoke on Friday, one day after Okinawa police informed the prefectural government about a case involving a US Marine after it was referred to prosecutors. The man in his 20s is suspected of sexually assaulting a woman and injuring her.

It was the first case reported by police under an information-sharing system, which was set up in July after a series of sex crimes involving US service members in Okinawa came to light. Prefectural officials had not been informed of the cases, either by local police or the central government.

Governor Tamaki told reporters that inhumane and abhorrent crimes committed by US military personnel are totally inexcusable, and that strong protests must be lodged against both the US and Japanese governments.

He said it is important to urge both governments to take steps to prevent a recurrence, so prefectural police must promptly provide information once a crime occurs.

The governor is due to visit the United States from Sunday. He suggested that the US military may be losing discipline, and that he will protest strongly.

Tamaki added that the information-sharing system has been affirmed by the foreign and defense ministers of the two countries, so he will call for efforts to make sure it functions effectively.