DELAYED: Boeing Starliner's first crewed mission lands in trouble again

The first crewed mission of Boeing's Starliner has been delayed once again despite being postponed for several years amid setbacks in the spacecraft's development.

According to officials at the National Aeronautics and Space Administration (Nasa), the decision to halt the mission was made two hours before its scheduled launch on Monday.

Nasa officials said that space flight was postponed for a safety check.

According to a BBC report, Nasa astronauts Butch Wilmore and Sunita Williams were already in position inside the Starliner capsule when a potential issue with an oxygen relief valve was detected in the Atlas rocket run by the United Launch Alliance (ULA).

According to the report, there was no issue with Boeing's Starliner Spacecraft which sits on top of the rocket.

Flight engineers discovered that the valve had been rapidly opening and closing in the period before launch and so the countdown was aborted.

The flight team is analysing data to determine the energy usage of the valve. It is also determining if it exceeds its operational life, will need replacement, which ULA say its engineers can do in a few days.

The spacecraft had been expected to blast off from Cape Canaveral in Florida and make its way to the International Space Station (ISS).

In a social media post, Boeing said that the soonest a new launch attempt may be made is on Friday.