Crew members for China's next two manned spaceflights have been selected and are undergoing extensive training, according to a senior space official.

Yang Liwei, China's first astronaut in space and now one of the chief planners of the nation's manned space program, told China Central Television that in addition to basic training, the Shenzhou XVIII and XIV crews have also been learning to perform some specific tasks on board the Tiangong space station.

"Scientific experiments, equipment installation, maintenance and repair work are major assignments for astronauts during their orbital stay," he said on a CCTV program on Wednesday.

Moreover, crew members are also being trained to deal with some unexpected scenarios and emergencies, according to him.

Yang told the State broadcaster that the Shenzhou XVIII and XIV manned missions and the Tianzhou 8 robotic cargo ship are scheduled to be launched this year

Orbiting Earth at about 400 kilometers above the ground, Tiangong has three permanent parts — a core module and two science capsules — and is regularly connected to several visiting crew and cargo spaceships.

Currently, the colossal flying outpost is manned by three astronauts with the Shenzhou XVII mission who arrived on Oct 26.

The Shenzhou XVII team, the sixth inhabitants of the Tiangong, is scheduled to return to Earth around April after living in space for about six months.