A Chinese astronaut completed a space walk Saturday, state television said, as the Asian power became the third nation to perform the feat after the United States and the former Soviet Union.

Mission commander Zhai Zhigang left the Shenzhou VII spacecraft at about 4:45 pm Beijing time (0845 GMT) to float in orbit for just under 15 minutes, according to the live TV transmission.

"I feel well," said Zhai, the leader of the Shenzhou VII's three-man crew, waving to a camera outside the spacecraft. "I am greeting the Chinese people and the people of the world."

The space walk was the highlight of the 68-hour voyage -- China's third manned foray into space -- and considered an important step towards building a space station, China's next major ambition in space.

In a highly symbolic move, Zhai waved a small Chinese flag shortly after climbing out of the spacecraft 343 kilometres (215 miles) over the Earth.

Tethered to the craft with two safety wires, Zhai, 41, slowly moved towards a test sample of solid lubricant placed outside the orbital module, Xinhua news agency said.

He took the sample and handed it over to fellow astronaut Liu Boming, who stayed in the orbital module and closely monitored Zhai's moves.

The move was a drill intended to replicate the type of task that future space walkers will have to perform. No immediate explanation was given for why the walk was shorter than the expected 20 minutes.

President Hu Jintao had appeared at the Beijing Aerospace Control Centre to watch the live transmission of Zhai's spacewalk, Xinhua news agency said.

The spacewalk had been eagerly anticipated, while state media had also pointed out the risk associated with the activity.

An "intensive psychological shock" would be unavoidable once the astronaut left the capsule, Xinhua said earlier, citing Yang Liwei, who piloted China's maiden space flight in 2003.

The Chinese Internet offered a forum for local enthusiasts to express their pride over the fledgling space power's achievements.

"Go China! Go Zhigang! We wish you good luck!" Said a typical posting on popular web portal Sina.com.

The astronauts, who took off from the Jiuquan Satellite Launch Centre in the desert of northwest China late Thursday, had passed most of their first day in space preparing for the walk.

On Friday, Zhai and his colleague Liu Boming spent 12 hours unpacking and assembling the special China-made space suit that must be used during the walk outside the Shenzhou craft.

It was the first time the two tried to assemble the suit in conditions of perfect weightlessness as it is impossible to create a real zero-gravity environment on Earth, the paper said.

As part of China's space programme, two more unmanned craft will be launched by 2010, as well as another manned spaceship with a crew of three to start work on the lab or space station, according to the China Daily.

After China sent its first man into space in 2003, it followed up with a two-man mission in 2005.

The astronauts also had time Friday to enjoy the view, witnessing 16 sunrises during their first 24 hours in orbit, and to sample the 80-dish menu they brought with them on their 68-hour mission.

Sleep was necessarily limited, but the spacecraft has sleeping bags hooked to the wall of the craft. However, the astronauts were told to keep their hands inside the bags in order to avoid them accidentally pushing a button or flipping a contact while asleep, Xinhua said.

The Shenzhou VII is scheduled to land in the northern Inner Mongolia region after the mission is completed.