WASHINGTON (Reuters) - The U.S. State Department notified Congress on Wednesday that it has approved a possible sale of Boeing Co <BA.N> military refueling aircraft to Japan worth up to $1.9 billion, the Defense Security Cooperation Agency said.

The agency said in a statement that Japan is seeking four KC-46A aerial refueling aircraft plus an additional spare Pratt & Whitney <UTX.N> turbofan engine as well as other supporting systems. The estimated cost of the aircraft and other equipment is $1.9 billion, DSCA said.

(Reporting by David Alexander; Editing by Eric Walsh)