Xinhua news agency said Shenzhou IV touched down in Inner Mongolia in northern China, six days after its launch into space.

Shenzhou IV is China's fourth unmanned spacecraft to successfully complete its mission and is regarded as the final precursor to a manned space flight.

The United States and the former Soviet Union are the only other nations to independently send a human into orbit.

Compared with the three previous unmanned space capsules China launched between November 1999 and March 2002, Shenzhou IV represents the country's most sophisticated mission, Yuan Jie, director of the Shanghai Aerospace Bureau, said last week.

Officials have said Shenzhou IV launched with all the prerequisites for a manned flight and even had spare clothes that astronauts might need to change into.

Two previous unmanned spacecrafts put into orbit by China, the Shenzhou II and Shenzhou III, were also capable of manned flight but the Shenzhou IV system guaranteed astronauts' complete safety, Xinhua quoted Qi Faren, the spacecraft's chief designer, as saying Friday.

"We have designed and tested eight systems altogether to ensure that the astronauts can escape at every stage of the flight if there is an accident," Qi said.

Astronauts even had some training time in Shenzhou IV before it hit the launch pad, maneuvering around equipment that had been rearranged to simulate comfortable living and working arrangements inside the capsule.

The satisfactory performance of the Long March 2F rocket, which helped the spacecraft blast off, also boosted Chinese confidence that a manned flight was imminent, the China Daily said.

The Shanghai Aerospace Bureau's Yuan has said this will happen in the second half of the year, although this is not a foregone conclusion.

The Chinese space programme, set up in 1992, is run by the military and is shrouded in official secrecy.

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