A comet-like object has been created by the collision of two asteroids related to the one blamed for killing the dinosaurs millions of years ago.

The object, known as P/2010 A2, was circling 90 million miles from Earth in the main asteroid belt between Mars and Jupiter when it was spotted last week by the Hubble Space Telescope.

'The truth is we're still struggling to understand what this means,' lead scientist David Jewitt with the University of California at Los Angeles. 'It's most likely the result of a recent collision between two asteroids.

If so, he said, 'It'd be the first case we've seen of an asteroid smash happening, basically caught in the act.'

The object resembles a comet, but its nucleus is severed from its tail, which 'has a very strange appearance, the likes of which we've never seen before,' Mr Jewitt said.

Studies of the object - and searches for similar ones - would improve scientists' understanding of how asteroids break apart..

That information may be useful to thwart a future asteroid strike on Earth.

'The thing that we want to understand is how the asteroids smash into each other and destroy each other,' Mr Jewitt said.

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This Hubble Space Telescope picture shows a bizarre X-pattern of filamentary structures near the point-like nucleus of the object and trailing streamers of dust

'It might help us understand even how to destroy an asteroid and prevent one from hitting us.'

Scientists believe a giant comet or asteroid that hit Earth about 65 million years ago was linked to the extinction of the dinosaurs.

One theory says the object threw up dust or chemical clouds that blocked the sun or that it ignited global wildfires.

Calculations show the orbit of P/2010 A2 is related to the group of asteroids, known at the Flora family, that produced that asteroid.

Nasa is working to catalogue at least 90 per cent of the estimated 1,000 objects that approach Earth and are larger than two-thirds of a mile across.

The agency's proposed budget for the year includes a $16 million (£10 million) annual increase to step up that effort.