Three Chinese astronauts made final preparations Wednesday for a mission that will include the nation's first ever space walk, saying they were confident of handling what will be a difficult but historic voyage.

Zhai Zhigang, Liu Boming and Jing Haipeng, all born in 1966 and all holding the rank of colonel, saluted stiffly as they appeared before journalists inside the Jiuquan Satellite Launch Centre in a remote desert area in northwest China.

"I have lived, studied and trained with Zhigang and Haipeng for the past more than 10 years," said Liu, sitting in his blue astronaut uniform, separated from reporters by a window pane to avoid contamination.

"Especially in our training for Shenzhou VII, it's been going so well that we can cooperate without even having to use words."

The launch is scheduled for between 9:07 pm and 10:27 pm (1307 and 1427 GMT) on Thursday, Wang Zhaoyao, a spokesman for the manned space programme, told an earlier press conference.

"Shenzhou VII is a new breakthrough, a new leap, for our manned space programme," Zhai said in the televised press conference.

"It's a glorious mission, with historical significance. It's the highest honour for us astronauts to travel into space as representatives of the motherland."

The Shenzhou -- whose name means "Divine Vessel" -- will move into orbit at an altitude of 373 kilometres (230 miles) for the space walk, which is expected Friday or Saturday.

Wang, the spokesman, warned that this mission was much more challenging than the previous two manned space flights in 2003 and 2005 because of the space walk.

"Difficulty has accompanied us all along, but not a single of our astronauts has been scared of these difficulties," said Jing, one of the astronauts.

Colleague Liu Boming added: "I believe China's astronauts are the best."

One of the astronauts, whom government websites have identified as Zhai, will test a new Chinese-made spacesuit on the space walk.

"One astronaut will get out of the cabin and bring back test samples loaded outside the module," Wang said.

A second astronaut will join Zhai in a decompressurised orbital module during the manoeuvre.

Zhai's backup is not due to leave the orbital module but will do so in case of any possible malfunction of the spacesuit, which reportedly cost up to 160 million yuan (23 million dollars).

The Shenzhou VII is scheduled to land in the northern Inner Mongolia region after the mission -- due to last around 68 hours -- is completed.

The aircraft is made up of a service module that powers the craft, a return module and an orbital module that has the capability to stay in space after the astronauts return to earth.

China became only the third nation after the United States and Russia to independently put a man in space when Yang Liwei, a fighter pilot, flew aboard the Shenzhou V in October 2003.

The latest mission will be closely watched by the United States, among others, after China shot down one of its own satellites last year in a move that raised international concerns over its military ambitions in space.