Two Chinese astronauts on Sunday performed a spacewalk, first for China, outside China's new orbital station, Tiangong around Earth. The two astronauts worked for around seven hours in the first spacewalk at Tiangong to set up a 15-meter (50-foot) long robotic arm, the China Manned Space Agency said.

They installed foot stops on the station's robotic arm and carried out other assembly work with its support, the space agency said.

"The safe return of astronauts Liu Boming and Tang Hongbo to the Tianhe core module marks the complete success of the first spacewalk in our country's space station construction," the space agency said.

Also Read | No rest in space: Chinese astronauts record their hectic day in station

The construction of the Tiangong space station comes as China this year has already made a landing on Mars and sent probes to the Moon.

Three Chinese astronauts in June took off to become the first crew of Tiangong, where they will spend three months, which China's longest crewed mission to date.

The two of three astronauts' tasks involved elevating a panoramic camera outside the Tianhe core module, testing the station's robotic arm that will be used to transfer future modules around Tiangong, according to Chinese state media. The two astronauts were supported by mission commander Nie Haisheng, an air force pilot who is on his third space mission, from inside the station. 

Also Read | Hubble space telescope down due to a fault in payload computer: NASA

"Wow, it's too beautiful out here," Liu Boming said while leaving the cabin, a video clip showed. 

This was the first of the two spacewalks, each expected to last six or seven hours, planned for the mission.

It was the first time after 2008 when Chinese astronauts went outside their spacecraft. In 2008, Zhai Zhigang made China the third country to complete a spacewalk after the Soviet Union and the US, AFP reported. 

This is China's first crewed mission in nearly five years and it came alongside the nation's marking 100 years of the ruling Communist Party this month.

Tiangong is expected to have a lifespan of at least 10 years, and China has said it would be open to international collaboration on the station.