The supply ship Progress M1-2 was launched on a Soyuz booster rocket at 2008 GMT Tuesday from the Baikonur cosmodrome in Kazakhstan and jettisoned the rocket 10 minutes later, Russian space officials told the ITAR-TASS news agency.

The ship is scheduled to dock with Mir early Friday, ITAR-TASS said.

The cargo weighing over two and a half tonnes includes fuel to raise the space station's dropping altitude, food, water, oxygen reserves and equipment for the two Russian cosmonauts on board.

Sergei Zalyotin and Alexander Kaleri, on the first privately-financed mission to the 14-year-old station, have been in orbit for almost three weeks. It is the 28th mission to Mir, which is leaking air and had been uninhabited since August 1999.

Deputy flight chief Victor Blagov told Interfax Tuesday that the cosmonauts had found one of the micro-air leaks plaguing the station, but said he was more worried about the evident decrease in Mir's altitude.

"With the active sun this year, the altitude is lowering quite noticeably and it would take a large amount of fuel to lift the 120-tonne orbital complex," he said.

Mission control said Mir is corrected regularly and each time the station is moved a few kilometres higher. The last correction was with the help of engines from the Progress M1-1 cargo ship on Monday.

The orbital parametres are now 353 km (apogee) and 329.4 m (perigee). The station had earlier worked at an altitude of about 400 km, Interfax reported.

The cosmonauts' tasks included plugging the holes through which air is slowly leaking and to pump in fresh oxygen supplies.

The tests have found that air is leaking through the hermetic plate connecting cables between the Spektr module, which was depressurised as a result of an accident, and the station's transfer compartment, Interfax said.

Russia has been criticised by the United States for abandoning previous plans to deorbit the space station and for funding new missions whilst delaying progress on the construction of the International Space Station.

Blagov said Russia was "acquiring experience to use on the international space station."

Mir had been due to come down to Earth last summer because Russia's cash-strapped space programme was unable to fund both Mir and its share of work on the multi-billion dollar ISS project.

Mir was the pride of the Soviet space programme when launched in 1986 but has been plagued with technical problems. However, Mir's Russian operator Energia says it is still capable of functioning for two or three more years.

The last cosmonauts to have lived on Mir were two Russians, Viktor Afanassiyev and Sergei Avdiyev, and the French astronaut Jean-Pierre Haignere, who ended their mission August 28.

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