The three astronauts aboard China's Shenzhou XVIII spaceship have completed in-orbit handover from the Shenzhou XVII crew members on Sunday, China Manned Space Agency announced.

A handover ceremony was staged between the two Shenzhou crews. The keys to the Tiangong space station have been exchanged to the Shenzhou XVIII crew members of Ye Guangfu, Li Cong and Li Guangsu. The handover process is a crucial step to ensuring the safety of both crews and the success of the upcoming missions, the CMSA said in a statement.

The Shenzhou XVIII spacecraft successfully docked with the radial port of the China Space Station's core module Tianhe at 3:32am on Friday after being launched at 8:59pm on Thursday from the Jiuquan Satellite Launch Center in Northwest China.

It added that the Shenzhou XVII crew members, consisting of Tang Hongbo, Tang Shengjie and Jiang Xinlin, who were launched to the Tiangong space station last October have completed all the missions and will return to the Dongfeng landing site in North China's Inner Mongolia autonomous region on Tuesday.

At present, the landing site and all participating systems are making final preparations to welcome the astronauts back.