The privately-owned reusable Dragon cargo spacecraft carrying more than 1,000 lbs (some 450 kg) of supplies docked on Wednesday with the International Space Station, NASA's website said.

ISS astronauts Sunita Williams and Akihiko Hoshide have used the 17-meter Canadarm robot arm to grab the Dragon vessel, which arrived earlier today, and pulled it to the station, completing the operation 40 minutes ahead of schedule.

It is the first of 12 flights to the ISS that US private space transport company SpaceX is carrying out under its $1.6-billion Commercial Resupply Services contract with NASA.

The Dragon will be docked at the orbital station for about three weeks before departing back to Earth.

It is the only space freighter capable of bringing back research and other items from the ISS, as Russia’s Progress, European ATV and Japanese H-II vehicles are not reusable.

The Dragon made a demonstration flight to the space station in April.

NASA has also signed a contract with another US company, Orbital Sciences Corporation, for eight resupply missions to the ISS.

The first flight of its Cygnus cargo spacecraft to the orbital station is expected in 2013.

Cygnus does not provide return capability but can be loaded with obsolete equipment and trash for destructive reentry similar to the Russian Progress vehicles.