(Reuters) - The Pentagon's Missile Defense Agency said on Wednesday that it had added $120 million to an existing Raytheon Co contract for work on the SM-3 missile, bringing the total value of the deal to $809 million.

The contract change allows Raytheon to continue working design, engineering and flight test support for the missile and to transition to production, the Pentagon said in its daily digest of major weapons contracts.

The contract runs through September 30, 2015.