Astronauts aboard the International Space Station (ISS) reached out and caught SpaceX's Dragon capsule for docking at the orbiting lab in a historic first for commercial spaceflight.

"Capture is confirmed," said NASA at 9:56 am (1356GMT) on Friday, ahead of a second-phase operation to attach the cargo-carrying Dragon to the lab as the two spacecraft zoomed 400km over northwest Australia.

"It looks like we got us a Dragon by the tail," said US astronaut Don Pettit, who was operating the Canadian-built 17.7m robotic arm from the space station as it reached out and hooked on to the unmanned SpaceX capsule.

The California-based SpaceX, owned by internet entrepreneur Elon Musk, has now reached the climax of its test mission to become the first privately owned craft to reach the space station, restoring US access to the space outpost.

With no humans on board, the capsule is delivering about a half ton of supplies and science experiments for the ISS, and aims to return a slightly larger load of gear to Earth on May 31.

'New era'

The two spacecraft were traveling about 402km above northwest Australia at the time of the grab, NASA said.

Next, a formal berthing of the Dragon will bring the capsule closer to latch on at the station's Harmony module so its cargo can be unloaded over the coming days, SpaceX said.

The US space shuttle program ended last year, leaving only Russia capable of carrying astronauts to the ISS and the space agencies of Russia, Japan and

Europe capable of cargo missions to service the $100bn space station.

SpaceX hopes its Dragon capsule will be able to carry astronauts to the ISS in about three year's time.

The launch marked the first time a commercial enterprise has sent its own craft to the orbiting lab and opened what NASA, the White House and SpaceX officials described as a "new era" in spaceflight.