A Chinese space station has begun its out-of-control descent towards Earth's surface and is expected to crash-land within a few months.

Launched in 2011, the 8.5-ton Tiangong-1 space laboratory had originally been a symbol of Beijing's ambitious scientific bid to become a space superpower.

However, last year Chinese officials confirmed the country's first orbiting space station had to be scrapped after its functions failed following two years in space.

Since then, the space station known as "Heavenly Palace" has been gradually decaying and, in recent weeks, has accelerated its descent into the Earth's atmosphere.