Mir will splash down into the Pacific "around 0800 GMT", a spokesman for the Russian mission control centre told the news agency AFP.

Any remnants of the 15-year-old craft that do not burn up in the Earth's atmosphere should splash down in a remote part of the ocean between South America and New Zealand.

Russian space officials have signed a deal with three insurance companies to a sum of $200m (£139m) to cover any possible damage from falling fragments.

Offical reassurance

Several governments have expressed concern that the space station might miss its target.

US astronaut Shannon Lucid spent 179 days on Mir

The 16-nation Pacific Forum has demanded reassurances from Russia that its nations will not be threatened by Mir's descent.

On Thursday, Russian Embassy officials sought to reassure Chileans that there was no risk of radioactive contamination from Mir's destruction.

Russian space officials revealed on Wednesday that the space platform has rapidly lost height. Mir has now reached an orbit of 241 kilometres (149 miles) above the planet.

Rocket firings

It only has to descend another 21 kilometres (13 miles) to re-enter the Earth's atmosphere where it will burn up.

The craft's final descent is expected to start late on 21 March. Russian ground controllers will direct a rocket engine to fire three short bursts, causing the complex to tilt and plunge towards the Earth.

The station should be largely destroyed on re-entry but around 1,500 pieces of debris, about 20 tonnes in weight, are expected to fall into the ocean.

The space platform, launched in 1986, is being brought to Earth because Russia cannot finance its commitment both to Mir and to the 16-nation International Space Station.