A U.S. firm aborted on Saturday the lift-off of the first commercial cargo ship to the International Space Station (ISS) after an engine cut-off, NASA said. The engines of Spacex\'s Falcon 9 rocket were shut down after onboard computers noticed a high pressure warning just as the vehicle was about leave the pad at the Cape Canaveral Air Force Station in Florida. SpaceX head Elon Musk wrote on his Twitter account: \"Launch aborted: slightly high combustion chamber pressure on engine 5. Will adjust limits for countdown in a few days.\" The next opportunity to launch the unmanned rocket carrying the Dragon cargo capsule is on Tuesday. SpaceX is one of two private companies which have been awarded billion-dollar contracts by NASA to fly cargo to the ISS. The firm also hopes in future to carry atronauts to and from the orbital outpost.