Chinese scientists are constructing the world's biggest radio telescope, which will be more effective than any other at picking up weak messages from outer space that could be linked to intelligent life.

Assembly of the Five-hundred-metre Aperture Spherical Telescope, or FAST, began in July and is expected to be completed in 2016.

Once finished, the reflector dish of the telescope will be 500 metres in diameter, replacing Puerto Rico's Arecibo Observatory, only 300 metres in diameter, as the world's largest. 

The wider the dish, the more effective the telescope becomes at picking up weak messages from outer space.