The launch of "mega-constellations" of thousands of communication satellites could lead to a rise in collisions and build-up of space junk in the Earth's orbit, scientists have warned.

A decrease in the cost of the manufacture of satellites is set to lead to the deployment of hundreds or thousands into space from next year, creating a massive rise in the number of active satellites from the 1,300 currently in use.

But Dr Hugh Lewis, senior lecture in aerospace engineering at the University of Southampton, has warned a 200-year computer simulation has shown the creation of a mega-constellation could create a 50 per cent increase in the number of "catastrophic collisions" between satellites.