China's third manned spaceship, Shenzhou VII, set to launch in October, reached the Jiuquan Satellite Launch Center in the northwestern Gansu Province on Thursday, a source with the launch center said.

The spacecraft was transported to the launch center by air from Beijing early on Thursday morning, the source said, adding the move marked the start of the Shenzhou VII launch mission.

He said the spacecraft would be assembled at the launch center after experts finish examining its air tightness and electric properties, as well as conducting a series of other tests.

The experts had already run two rounds of tests on more than 5,000 pieces of equipment at the launch center to ensure reliability and the safety of the ground facilities.

The launch center has organized trainings of test launch, observation and control communication, and technical support to ensure the successful launch of the Shenzhou VII.

China successfully put two manned spacecraft into orbit in 2003 and 2005 respectively. Shenzhou VII was expected to be launched in October, although the exact date was not available.

Earlier reports said a crew of six astronauts had been chosen for the mission, with three manning the spacecraft and three substitutes.

Compared with Shenzhou VI, China's second manned space mission with a crew of two, Shenzhou VII has more stringent technological requirements: one of its three astronauts is scheduled to conduct a space walk.

China launched a new space tracking ship on April 12 to serve the Shenzhou VII spacewalk mission.

The new space tracking ship was the sister ship of the Yuanwang-5, which was put into use in September. The two vessels would play a key role in the Shenzhou VII mission.