UPDATE 1-Boeing delays flight test to International Space Station -sources

Boeing Co has delayed by at least three months its first uncrewed flight to the International Space Station under NASA's human spaceflight program, and pushed its crewed flight until November, industry sources said on Wednesday. Reuters reported last month that NASA has warned Boeing and rival contractor SpaceX of design and safety concerns the companies need to address before flying humans to space.

Boeing's first test flight was slated for April but it has been pushed to August, according to two people with direct knowledge of the matter. The new schedule means that Boeing's crewed mission, initially scheduled for August, will be delayed until November. A Boeing spokesman declined to comment.

NASA spokesman declined to comment but said a new update to the launch schedule would be posted next week. NASA is paying Boeing and SpaceX about $6.8 billion to build rocket and capsule launch systems to return astronauts to the International Space Station from U.S. soil for the first time since America's Space Shuttle program went dark in 2011.

Earlier this month an unmanned capsule from Elon Musk's SpaceX completed a six-day round-trip mission to the International Space Station. It's astronaut flight is planned for July. (Reporting by Eric M. Johnson in Seattle and Joey Roulette in Orlando, Florida; editing by Grant McCool)