WASHINGTON, Dec. 23 (Xinhua) -- The U.S. navy has signed a contract worth some 14 billion U.S. dollars with General Dynamics and Northrop Grumman to build eight new Virginia-class submarines, the companies said Tuesday.

    In a statement, General Dynamics said its Electric Boat unit and Northrop Grumman Shipbuilding, a unit of Northrop Grumman, will start building the submarines next year.

    The companies said they will build one submarine each year in 2009 and 2010, and two a year from 2011 through 2013.

    Virginia-class submarines displace 7,800 tons, with a hull length of 114.9 meters and a diameter of 10.36 meters, the statement said.

    These submarines are capable of speeds in excess of 25 knots (46 km per hour) and can dive to a minimum depth of 244 meters, while carrying Mark 48 advanced capability torpedoes, Tomahawk land attack missiles and unmanned underwater vehicles.