The US Navy has awarded a contract worth $260m to Raytheon for carrying out additional work on its ship weapons system.

Under the contract, 16% of the work will be performed in Tucson, while the remainder will be divided between other Raytheon sites in eight states.

The company will perform upgrades on the MK15 Phalanx close-in weapon system, which is a multi-barrelled machine gun installed on ships to destroy high-speed missiles.

The weapon system has been used on 187 navy ships and in 20 foreign navies. Work is expected to be complete by September 2012.