Astronomers in New Mexico spotted asteroid 2002 NT7 on July 5. They calculated that the asteroid, estimated between two and four kilometres in diameter, had a one in 60,000 chance of hitting Earth on February 1, 2019.

"Today, calculations show a one in 60,000 chance that the asteroid will strike the Earth," Alan Fitzsimmons, scientist at the National Space Centre in Leicester, central England, told The Guardian newspaper on Thursday.

A British parliamentary deputy has urged the government not to ignore the threat.

Lembit Opik, from the Liberal Democrats, Britain's third biggest party, said: "I have said for years that the chances of this asteroid having an impact which could wipe out most of the human race is 100 percent.

"There's a good chance this particular object won't hit us but we know that a large object will hit us sooner or later. This is the closest approach we have seen so far."

The asteroid, travelling at 28 kilometres per second, could cause tidal waves, massive fires and volcanic activity, added Opik.

Asteroids are often described as the rubble left over from the building of the solar system.

They orbit the Sun, but the paths are never eternal, and their trajectories can be deflected by gravitational pull whenever the asteroid passes by a planet.

A football-pitch-sized asteroid capable of razing a major city came within a whisker of hitting the Earth on June 14.

Asteroid 2002 MN, estimated at up to 120 metres (yards) long, hurtled by the Earth at a distance of 120,000 kilometers (75,000 miles), well within the orbit of the Moon and just a hair's breadth in galactic terms.

It is the closest recorded near-miss by any asteroid, with the exception of a 10-metre (33-feet) rock, 1994 XM1, which approached within 105,000 kilometers on December 9, 1994.

SPACE.WIRE