An American sailor has been arrested for an alleged rape on the Japanese island of Okinawa, in a case that could inflame local resentment against the US military presence.

Police arrested Justin Castellanos, 24, a US Navy seaman at Camp Schwab, on Sunday.

He allegedly assaulted a Japanese tourist in her 40s at a hotel earlier that morning.

The sailor dragged the woman into his room and raped her after finding her asleep in the hallway, reports Kyodo News agency.

An Okinawa demonstration against the US military in August 2014

Castellanos has not been formally charged.

According to the Asahi Shimbun newspaper, the two were staying at the same hotel, but were not acquainted.

Japan's Chief Cabinet Secretary Yoshihide Suga said: "We promptly told the US side this is extremely regrettable and demanded firmly stricter discipline and prevention of recurrence."

Okinawa Governor Takeshi Onaga told reporters the case is "a serious crime and blatant violation to women's human rights".

Okinawa, the site of a fierce World War II battle, hosts about half of the 50,000 American troops in Japan.

The island's residents have frequently protested against the US bases, complaining about noise and crime from the facilities.

A 1995 rape of a 12-year-old schoolgirl by three US servicemen caused uproar on the island.

The case led to an agreement to move a US Marine base to a less crowded part of Okinawa.

The relocation plan was placed in limbo this month because many residents want it entirely off the island.

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