NEW YORK, May 19 (Xinhua) -- The Somali teenager, who is accused of being involved in the hijacking of an American ship last month, is indicted on piracy charges in New York, authorities said Tuesday.

    Last month, a New York judge ruled Abdiwali Abdiqadir Muse should be tried in open court despite arguments from his lawyer that he was 15 and should be tried as a juvenile.

    Muse, 18 years old, the only pirate to survive the siege, has been jailed in Manhattan since he was captured on April 12 and flown to the United States to face what's believed to be the first U.S. piracy prosecution in more than a century.

    If convicted on the piracy charges, Muse could face a mandatory sentence of life in prison.

    Prosecutors believe Muse was the ringleader of the crew that hijacked the Maersk Alabama and held Captain Richard Phillips hostage for five days.

    Phillips was freed when U.S. Navy SEALS, the Special Operations Forces of the United States Navy, killed three of the hijackers.

    Muse's mother had appealed to President Obama for his release saying her son is just 16 years old.