Thousands of protesters in the southern Japanese prefecture of Okinawa have demanded that the US military give an apology and compensation to the victim in a sexual assault case one year ago.

Organizers say about 2,500 people took part in the protest meeting in the city of Okinawa on Sunday.

Brennon Washington, a 25-year-old US serviceman from the Kadena Air Base in Okinawa, was accused of abducting and sexually assaulting a girl under the age of 16 at his residence in December last year. Authorities say the two were not known to each other.

A court in Okinawa sentenced the man to five years in prison on December 13.

Okinawa Governor Tamaki Denny was among the protesters. He said many residents of Okinawa have been forced to coexist with US bases under a cloud of anxiety, and that Okinawans must raise their voices and take stronger action.

A university student representing young residents asked why they have to be deprived of their adolescence just because they were born in Okinawa near US bases. She added that a similar incident must never happen again.

The protesters adopted a resolution demanding that the serviceman and the US military offer an apology and compensation to the victim.

The document also urges the Japanese and US governments to immediately share information with the prefecture if a similar incident were to occur.

The organizers say they will deliver the resolution to the two governments.