MONTREAL - SCIENTISTS and amateur astronomers were combing the prairies in western Canada for a 10-ton meteorite that lit the sky and exploded with the force of 300 tonnes of dynamite, two experts from the Canadian Space Agency said on Tuesday.

The meteorite, seen on Thursday by thousands of people in a 700km radius, fell south-east of Lloydminster, near the border between Saskatchewan and Alberta provinces, astrophysicists Alan Hildebrand and Peter Brown said in a statement.

At the moment it entered the atmosphere, the asteroid fragment weighed approximately 10 tonnes, from an energy estimate derived from infrasound records, said Prof Brown, professor of meteor physics at University of Western Ontario.

'The indicated energy is approximately one third of a kiloton of TNT,' he added.

Hundreds of fragments of the meteorite weighing more than 50g were likely strewn over a wide area since its the speed of entry, some 14km per second, was well below the average 20km per second of most meteorites, said University of Calgary researcher Mr Hildebrand.

Most meteorites fall to earth at such a high speed that they burn up completely before reaching the ground.

The fireball enveloping the chunks of meteorites, which Mr Hildebrand likened to a billion-watt lightbulb shining in the sky, was filmed by several people, whom researchers have been tracking down since Friday in the area.

'We are now trying to get all the transient information about the fireball before it is lost,' Mr Hildebrand said.

'Many motels and gas stations only keep their security recordings for one week or less, so we urge everyone to check their systems to see if they recorded the fireball or the moving shadows that it cast,' he added.

Mr Hildebrand and Prof Brown are members of the Small Bodies Discipline Working Group that is funded by the Canadian Space Agency. -- AFP