A U.S. Navy sailor is under investigation for allegedly assaulting a Japanese woman, U.S. and Japanese authorities said Thursday.

The 26-year-old man, whose name was not released, was taken into custody after reportedly assaulting his 21-year-old Japanese girlfriend, U.S. Navy officials said.Japanese police said the sailor was suspected of lifting the woman in the air and slamming her against the floor, breaking her collarbone. He had been dating her for eight months.

The two apparently had a fight that escalated early Tuesday in the barracks at the U.S. naval base at Yokosuka, just outside Tokyo, Jap-an-ese police said.

U.S. Navy officials said the woman accused the sailor of sexually assaulting her, but the Navy and Japanese police said they are not conducting a rape investigation.

The woman was taken to the Navy hospital at the base and treated for a fractured left clavicle, contusions and abrasions and then released, the U.S. Navy said.

Yokosuka police said they are planning to ask Navy authorities to turn the suspect over to Japanese custody. The sailor was being questioned by the Navy Criminal Investigative Service.

The incident comes just before U.S. Defense Secretary William Cohen's visit next week to discuss bilateral security alliance and could further embarrass the U.S. military in Japan.

Anger against American forces in Okinawa boiled up after a 12-year-old girl was raped by three U.S. servicemen in September 1995 and again this year after news that American troops in training had accidentally fired bullets containing uranium.

Washington and Tokyo have agreed to move some U.S. facilities out of Okinawa, but the island still home to 75 percent of the 47,000 U.S. troops based in Japan.

Thursday, Japan's Cabinet endorsed a bill aimed at allowing the government to legally expropriate land from Okinawa landowners who are refusing to lease it to the U.S. military.