China's fourth unmanned spacecraft, Shenzhou IV, has returned to Earth.

The official Xinhua news agency said it landed as planned on the central grasslands of the vast Inner Mongolia region, a replay of the conclusion of the three previous Shenzhou missions.

The craft had been in orbit since Monday.

It is thought that this was the last test flight before a manned mission planned for later in the year.

Taikonauts

According to the China Daily, the craft functioned normally and the experiments carried out on board were successful.

Shenzhou III returned to Earth safely in April last year

Rumours about China's manned missions have been rife for a number of years, although plans to build a Moon base have been denied.

To distinguish them from Russian cosmonauts and American astronauts, China uses the term "taikonauts" for its would-be space crews, deriving from the word "taikong" meaning space.

It is understood that about a dozen fighter pilots are training to become taikonauts, although there have been conflicting reports about how many have been chosen and where they are undergoing their training.

Previous success

The first test flight of the Shenzhou programme was in November 1999, when a capsule orbited the Earth 14 times in a 12-hour mission aimed at testing launch and re-entry systems.

Shenzhou II, launched in January 2001, circled the Earth 108 times and tested life support systems - it put a monkey, a dog, a rabbit and snails into orbit.

It returned nearly a week later to a press blackout that left Western analysts suspecting a re-entry failure. The Chinese authorities denied this.

Shenzhou is modelled on Russian space technology, but with wide-ranging modifications by Chinese engineers.

In April 2002, Shenzhou III carried out a successful week-long flight.

If the Chinese are successful, they would be only the third country to put humans into space, joining the United States and Russia.