Of almost 4500 satellites in orbit, only 1500 were active, the ESA chief said.

Thousands of inactive satellites are floating in space and pose a danger to humanity, the head of the European Space Agency (ESA) has warned.

Speaking at the agency's ministerial council in Seville, Jan Wö​rner said that of almost 4500 satellites in orbit, only 1500 were active. The ESA is working on plans to remove them, with firms such as Airbus developing technologies such as space harpoons and nets.

"We have the space debris, from upper stages, from adapters, from old satellites... a very big danger," Wörner said.

"We are proposing a mission [to] bring down some ESA-owned asset. And at the same time... we would also demonstrate that it's possible to avoid future space debris by doing also some direct de-orbiting."

READ MORE:

* 'Complex and diverse': NZ Space Agency reveals Rocket Lab customers' satellite plans

* Europe joins new space race with a mission to the Moon

* A new space power is born as China lands on the far side of the moon

* A space station is hurtling towards Earth - but you don't need to panic

* Thousands of tiny satellites are about to go into space and possibly ruin it forever

Space scientists are concerned that defunct models could collide with active satellites or the International Space Station, which would then cause more debris, setting off a catastrophic chain reaction that could wipe out telecommunications systems - a phenomenon known as Kessler Syndrome.

Wö​rner also called for missions to practice destroying or deflecting meteorites, describing it as like "playing billiards in space".

"The dinosaurs died out because of a meteorite, most probably," he said. "We don't want to be dying out because of a meteorite... and together with the Americans, we are proposing a mission in that."

NASA Space scientists are concerned that defunct models could collide with active satellites or the International Space Station, which would then cause more debris, setting off a catastrophic chain reaction that could wipe out telecommunications systems.

Ministers are meeting in Seville to discuss a schedule of space missions for the next few years.

Graham Turnock, the head of the UK Space Agency, said Britain would continue to play a "full part" in the ESA after Brexit. The UK also hopes to play a part in the Lunar Gateway, a space station intended to provide a stepping stone between the Moon and Earth.

"The UK is fully supportive of ESA's work to evolve and usher in a new era of space where we continue to push the boundaries of the possible," he said.