BEIJING, June 6 (Xinhua) -- China will carry out at least four manned spaceflight missions over about five years to build a space station, China's first astronaut Yang Liwei said Tuesday.

Two manned space missions will be conducted in 2020, said Yang, deputy director of China's manned space program office, at the 2017 Global Space Exploration Conference which opened Tuesday in Beijing.

China plans to complete the building of the space station by around 2022, aiming to carry out about a dozen launch missions beforehand, according to Yang.

He said the nation would launch the first core module of the space station in 2019, followed by launches of two experiment modules.

The space station will enable astronauts to stay in the space for three months to half a year, he added.

Yang said that astronauts are currently preparing for the space station program and that China will start the selection of new astronauts this year.