Beijing - China's Shenzhou VII manned spacecraft adjusted its orbit early Friday in preparation for the country's first spacewalk later in the day, the government said.

Shenzhou VII moved from an elliptical orbit to a circular orbit 343 kilometres above the Earth at 4:05 am (2005 GMT Thursday), state broadcaster China Central Television reported.

China launched three astronauts in Shenzhou VII on a Long March-2F carrier rocket Thursday night from the Jiuquan space centre in the north-western province.

The scheduled three- to four-day Shenzhou VII mission includes a spacewalk to be carried out by astronaut Zhai Zhigang at about 4:30 pm (0830 GMT) Friday.

Zhai is expected to spend about 40 minutes outside the spacecraft while he performs tasks such as retrieving a 3-kilogramme solid lubricant experiment from the rear of the spacecraft.

It would take him almost 15 hours to assemble and put on the 120- kilogram, 30-million-dollar protective suit for the spacewalk, state media said.

Shenzhou VII will release a 40-kilogram mini-satellite to monitor the orbital module and relay video images.

"The task will test our ability to observe and control two satellites in relative motion," Zhou Jianping, chief designer of the manned space programme, told the agency at Jiuquan.

The other two crew members are Liu Boming, who will assist Zhai with exiting and reentering the spacecraft, and Jing Haiping.

In 2003, the successful Shenzhou V mission made China the third country to launch a manned space mission after the former Soviet Union and the United States.

Shenzhou VI carried two astronauts into space in 2005.

Shenzhou VII is the next stage of China's plan to build an integrated ground-space network for space exploration and manned space research, including a permanent space laboratory by 2020. (dpa)