A 'massive meteorite' that blazed across the Australian sky was actually a three-tonne piece of space debris from a Russian rocket, experts believe.

Sightings of a bright burning object were reported from Victoria to New South Wales, passing over Melbourne, on July 10.

The space debris is believed to have been the upper state of the Soyuz rocket that was used to launch Russia's second Meteor-M weather satellite on 8 July.

Brian Schmidt, an astronomer at the Australian National University, explained Nasa had sent out an alert saying re-entry was likely: "Orbits of these [pieces of space junk] is monitored quite closely. This one was decaying rapidly and the prediction of the path was confirmed, because everyone saw it."

Nasa said the seven-metre, three-tonne object would fall back to earth over Victoria and Tasmania.

Nick Lomb, from the Sydney Observatory, said the space debris probably crashed into the Pacific Ocean near Brisbane. He told The Age that the event had been "rare and exciting" for astronomers, despite not being a celestial body.

Experts also noted that the object is one of the hundreds of thousands of pieces of space debris floating around Earth.

Ben Greene, chief executive of the Cooperative Research Centre at Mount Stromlo Observatory, said: "There is so much debris up there that it's colliding. A catastrophic avalanche of collisions could quickly destroy satellites worth trillions of dollars."

Indeed, a piece of space debris falling to Earth is expected to kill a human within the next 50 years.

Mr Greene said: "That's what we expect, but there's a higher chance of winning the lottery without buying a ticket."