Astronaut Zhai Zhigang is expected to undertake a spacewalk on Saturday afternoon, an event which will be broadcast live by state television.

The walk is expected to last for at least 20 minutes. The Shenzhou 7 spacecraft is China's third manned mission in past five years.

The mission is expected to last three or four days. China aims to assemble a permanent space station by 2020.

In October 2003, China became only the third nation after the United States and Russia to independently put a man in space.