Several asteroids have been photographed by spacecraft Worst case scenario

The mountain-sized object had been classed as a "potentially hazardous asteroid", but scientists said it posed no danger to Earth.

The asteroid 2004 XP14, as it is has been designated, was visible through good amateur telescopes.

Its closest approach to Earth, above the west coast of North America, occurred at 0444 GMT.

At this time calculations suggested it was about 432,709km (268,873 miles) from the Earth, only 1.1 times the planet's distance from the Moon.

Radar analysis

Scientists were using the occasion to work out the precise size and shape of the object by bouncing very high frequency radio waves off its surface.

POTENTIALLY HAZARDOUS ASTEROIDS Space rocks larger than about 100m that come closer to Earth than 7.5m km Astronomers have spotted 796 so far in this category They are under close scrutiny to better predict any threat

It will allow them to calculate precisely how close it came to the planet, as well as its velocity and mass, giving clues to its composition and structure - and future course.

2004 XP14 was discovered in December 2004 by telescopes run by the Lincoln Near Earth Asteroid Research (Linear) project.

Funded by the United States Air Force and the US space agency (Nasa), Linear aims to survey the sky for potentially dangerous asteroids.

Initially, there were concerns that asteroid 2004 XP14 might hit Earth later this century. But after further monitoring, astronomers ruled out such a collision for the foreseeable future.