China is preparing to launch a new three-person mission to complete work on its permanent orbiting space station, the China Manned Space Agency said.

The Shenzhou 14 crew will spend six months on the Tiangong station, during which they will oversee the addition of two laboratory modules to join the main Tianhe living space that was launched in April 2021.

Their spaceship is due to blast off from the Jiuquan Satellite Launch Centre on the edge of the Gobi Desert on Sunday morning, the agency said.

The crewed space flight programme’s workhorse Long March 2F rocket will provide propulsion.

Commander Chen Dong and fellow astronauts Liu Yang and Cai Xuzhe will assemble the three-module structure joining the existing Tianhe with Wentian and Mengtian, due to arrive in July and October.

Another cargo craft, the Tianzhou-3, remains docked with the station.

The arrival of the new modules will “provide more stability, more powerful functions, more complete equipment”, said Mr Chen, 43, who was a member of the Shenzhou 11 mission in 2016.

Ms Liu, 43, is also a space veteran and was China’s first female astronaut to reach space aboard the Shenzhou 9 mission in 2012.

Mr Cai, 46, is making his first space trip.

China’s space programme launched its first astronaut into orbit in 2003, making it only the third country to do so on its own after the former Soviet Union and the US.

It has landed robot rovers on the moon and placed one on Mars last year.

China has also returned lunar samples and officials have discussed a possible crewed mission to the moon.

China’s space programme is run by the ruling Communist Party’s military wing, the People’s Liberation Army, prompting the US to exclude it from the International Space Station.

Mr Chen, Ms Liu and Mr Cai will be joined at the end of their mission for three to five days by the crew of the upcoming Shenzhou 15, marking the first time the station will have had six people aboard.