A U.S. Marine who was accused of raping a 14-year-old girl in southern Japan has been released after prosecutors dropped the charges at the teenager's request, the Foreign Ministry said Friday.

Staff Sgt. Tyrone Luther Hadnott, 38, was arrested on Feb. 10 on suspicion of raping the girl on the southern island of Okinawa, fueling nationwide furor over crimes involving American troops in Japan.

Hadnott was released Friday night after the girl withdrew her criminal complaint against him, said Ryo Fukahori, a Foreign Ministry official in charge of Japan-U.S. security. Rape charges in Japan can be filed only with a victim's complaint.

Fukahori said the rape charges could be separately pursued by the U.S. military. Phone calls to the Marine Corps on Okinawa went unanswered, and the U.S. consulate said it had no immediate comment.

State Department spokesman Tom Casey told reporters Friday that the United States remains "very concerned about this incident" and has "great sympathies" for the girl and her family. He had no details about the legal process.

Japanese police earlier said Hadnott admitted that he forced the girl down and kissed her, but that he denied raping her.

A series of criminal accusations against some of the 50,000 American troops based in Japan have inflamed anger at the U.S. military presence.

In December, the U.S. military charged four servicemen in the rape of a 19-year-old woman in Hiroshima. Japanese prosecutors had dropped charges against the four, based in the U.S. Marine Corps Air Station in Iwakuni in southern Japan, citing lack of evidence.

The U.S. military has since imposed tight new restrictions on troops, their families and civilian expatriates in Okinawa and elsewhere, limiting them to bases, workplaces and off-base housing. The military held a "day of reflection" last week to urge troops not to commit crimes.

Japan also has introduced new security steps to curb crime around bases, including installing surveillance cameras and conducting joint patrols of entertainment districts around bases on Okinawa.