China sent three astronauts to its Tiangong space station Tuesday, putting a civilian into orbit for the first time as it pursues plans to send a crewed mission to the Moon by the end of the decade.

The world's second-largest economy has invested billions of dollars in its military-run space program in a push to catch up with the United States and Russia.

The Shenzhou-16 crew took off atop a Long March 2F rocket from the Jiuquan Satellite Launch Centre in northwest China at 9:31 am, AFP journalists saw.

The launch was a "complete success" and the "astronauts are in good condition", said Zou Lipeng, director of the Jiuquan Satellite Launch Center.

Dozens of employees from the space program, many of whom live year-round on the huge site, attended the launch, snapping selfies with the rocket in the background.

Children played as they waited for the launch, some waving Chinese flags as they sat on their parents' shoulders.

Spectators let out a loud "wow", shouting "good luck" and waving as the rocket took off in a cloud of ochre smoke.

Leading its crew is commander Jing Haipeng on his fourth mission, as well as engineer Zhu Yangzhu and Beihang University professor Gui Haichao, the first Chinese civilian in space.

China was the third country to put humans in orbit, and Tiangong is the crown jewel of its space program, which has also landed robotic rovers on Mars and the Moon.

Shenzhou-16 is the first mission to Tiangong since it entered its "application and development" stage, authorities said.

The Shenzhou craft will dock at the space station's Tianhe core module.

The crew will then meet their three colleagues from the Shenzhou-15 flight, who have been at the station for six months and will return to Earth in the coming days.

Shenzhou-16 will carry out a number of experiments during the mission, including in "high-precision space time-frequency systems", general relativity, and into the origin of life, CMSA spokesperson Lin Xiqiang told reporters on Monday.

The space station was resupplied with drinking water, clothing, food and propellant this month in preparation for Shenzhou-16's arrival.

One expert told AFP that Tuesday's mission represented "a regular crew rotation flight", but even that was significant.

"Accumulating depth of experience in human spaceflight operations is important and doesn't involve new spectacular milestones all the time," said Jonathan McDowell, an astronomer and astrophysicist at the Harvard–Smithsonian Center for Astrophysics.