SpaceX Falcon 9 launch postponed just moments before lift-off

An estimated 1.7 million people from around the world tuned in to the launch from The Kennedy Space Centre in Florida

Nasa has postponed its first launch of astronauts from US soil in nine years due to bad weather, just minutes before lift-off.

Robert Behnken and Douglas Hurley were set to travel to the International Space Station (ISS) on a rocket and capsule system built by billionaire entrepreneur Elon Musk's firm SpaceX.

An estimated 1.7 million people from around the world tuned in to the launch from The Kennedy Space Centre in Florida.

But as the weather conditions became worse, the US space agency "scrubbed" the mission for safety reasons less than 17 minutes before the Falcon 9 rocket was due to take off along with the Crew Dragon spacecraft.

The launch was cancelled due to three violations of weather rules - natural lightning, electric fields in the atmosphere and thunderstorm clouds.

The US Air Force's 45th Weather Squadron, which monitors the weather for air and space operations, had forecast between a 40% and 60% chance of favourable conditions at the launch site in Florida.

The earliest the astronauts can depart is this weekend, with potential launch windows available on Saturday and Sunday.

British astronaut Tim Peake said: "What a shame - @SpaceX launch is scrubbed, but the rules are there in the interest of safety.

"A great rehearsal and reset for the next launch attempt in 3 days, Sat 30th at 15:22 (ET)."