The Tiangong space station, the crown jewel of China's space programme, is crewed by teams of three astronauts exchanged every six months.

The return of the Shenzhou-20 spacecraft and crew had been planned for November 5, after the Shenzhou-21 mission arrived to relieve them.

However, because of the debris strike their return was delayed, and the three astronauts will come back aboard the Shenzhou-21 spacecraft instead, the China Manned Space Agency (CMSA) said in a statement.

It successfully separated from the space station at 11:14 am (0314 GMT) on Friday, state broadcaster CCTV reported.

The astronauts Chen Dong, Chen Zhongrui and Wang Jie are "all in good condition", CMSA said.

The Dongfeng landing site in northern Inner Mongolia is "making intensive preparations to welcome them home", it added.

The damaged Shenzhou-20 spacecraft will remain in orbit "to conduct relevant experiments", CCTV said.

Its window glass has "developed a minor crack", thought to be from the debris strike.

Billions of dollars have been poured into China's space programme in a bid to catch up with the United States and Russia.

Beijing has bold plans to send a crewed mission to the Moon by the end of the decade and eventually to build a base on the lunar surface.

CMSA said the Shenzhou-22 spacecraft will be launched at a later date, without giving any details.