Okinawa, Japan - A US Marine in Okinawa has been charged with non-consensual sexual intercourse resulting in injury, Japanese authorities said Friday, stoking discontent among residents over American military bases in the region.

The case came to light just days after it emerged that a US airman in Okinawa had been charged in March with raping a minor three months earlier.

Top government spokesman Yoshimasa Hayashi said local prosecutors had brought the new charge over another rape that allegedly took place in May.

In the latest case, the 21-year-old US Marine Corps member is accused of "assaulting the victim for the purpose of sexual intercourse and injuring her," an Okinawa police spokesman told AFP.

"The fact that he used violence for that purpose and wounded her constitutes non-consensual sex resulting in injury," the police spokesman said.

The woman had been "bitten in the mouth" and had taken two weeks to fully recover, he said. Media reports said she had also been choked.

The two cases have sparked outrage and echo Japan's fraught history with US troops, including the 1995 gang rape of a 12-year-old girl by three US servicemen.

Hayashi said on Friday the government has protested to US Ambassador Rahm Emanuel, calling for stricter oversight and steps to prevent a recurrence.

"We take it very seriously that a sexual crime allegedly committed by an American soldier happened again after the December incident by the US airman," Hayashi said.

"It is our understanding that the United States also appreciates the extreme gravity of what happened," he said.

Despite making up just 0.6% of Japan's landmass, Okinawa accommodates about 70% of all the US military bases and facilities in Japan.