Lockheed Martin has filed a formal appeal with the congressional General Accounting Office (GAO) against the awarding of a spy satellite contract to rival Boeing Co., a spokeswoman for GAO told space.com.

Earlier this month, the U.S. National Reconnaissance Office (NRO) awarded Boeing a multi-year contract to develop "the nation's next generation of imagery reconnaissance satellites." The decision was widely seen as a major blow to Lockheed Martin, which has long been a leading developer of spy satellites.

GAO, which is an investigative arm of Congress, provides a forum for companies to file "bid protests" against contracts they believe were awarded in violation of federal laws or regulations.