The U.S. Coast Guard has opened fire on a derelict Japanese vessel that was washed out to sea by last year's devastating tsunami and was drifting toward Alaska, a spokesman for the agency said on Thursday.

The Coast Guard, which hopes to sink the ship, fired on the vessel with a 25 millimetre machine gun, said Petty Officer First Class David Mosley, a spokesman for the Coast Guard.

(Reporting By Alex Dobuzinskis; Editing by Cynthia Johnston)