Three Chinese astronauts have been forced to extend their six-month stay in space over concerns that their return ship may have been hit by debris, China’s space agency said. No alternative date has been given for the return of the trio,

Two weeks ago, the Shenzhou-21 transported the three astronauts taking over from the Shenzhou-20 crew at the permanently inhabited space station known as Tiangong, or "Heavenly Palace".