China's space lab to fall back to Earth by weekend: Officials

China's first experimental space lab could fall back to Earth by the weekend but would not cause any damage to the ground, the Chinese military and space authorities said today.

The Tiangong-1, or Heavenly Palace 1, is orbiting at an average height of about 196.4 kms, the China Manned Space Engineering Office said.

It should burn up in the atmosphere, space have authorities said.

The approximate re-entry location cannot be determined until the last two hours before it starts to fall, China's space authorities reiterated, state-run Global Times said.

Small amounts of the space lab's fuel will be burned together with other parts, and will not cause damage to objects on Earth nor produce toxic substances, the daily quoted Chinese military officials as saying.

Earlier Chinese Defence spokesman Colonel Ren Gouging said China has briefed all relevant international agencies including the UN about the re-entry of the space lab.

Launched in September 2011, Tiangong-1, the experimental space station, had a design life of two years.

The heavenly vehicle successfully docked with the Shenzhou-8, Shenzhou-9 and Shenzhou-10 spacecraft and undertook a series of experiments.

The lab completed its main missions following Shenzhou-10's return in June 2013.

China plans to finalise its space station to rival Mir, the Russian space station currently in orbit by 2022.