Okinawa Prefectural Police have sent prosecutors papers on two U.S. Marines suspected of sexually assaulting women in the prefecture, police sources said Wednesday.

The cases of the Marines, both in their 20s, were referred to prosecutors April 7. The police reported the matter to the Okinawa government within the day.

One of the two is suspected of sexually assaulting an acquaintance in January, and the other of sexually assaulting a woman and injuring another at a military base in March, the sources said.

Both incidents came to light when the victims consulted police.

The suspects, who are both in the custody of the United States, accepted police interviews on a voluntary basis.

Last year, failure to share information with the prefectural government on sexual violence by U.S. soldiers became a problem.

In July last year, the prefectural police established a system to report such incidents to the prefectural government when arrests are made or papers are sent to prosecutors.

"It's very regrettable that such incidents have occurred," Okinawa Gov. Denny Tamaki said in a statement. "We strongly urge the U.S. military to take more effective measures to prevent a recurrence."