The head of the Gagarin Cosmonaut Training Centre, Petr Klimuk, said Peter Llewellyn had begun preparations on 21 May for a 10-day space flight but that the issue of financial aid, "the basic condition for this flight", had not been resolved.

"For this reason, on 25 May, the centre decided to halt Llewellyn's training with the Russian Cosmonaut Squad," he said.

The Russian authorities believed that Mr Llewellyn would deliver $100m of funding for the Mir space station. He denies any formal agreement was made.

The Star City cosmonaut training centre spokesman, Andrei Maiboroda, added: "He's a profiteer with whom it's better to not have contact."

"The garbage king"

Mr Llewellyn was a vice president of a subsidiary of RKK Energia, the company which runs Mir. His business interests in Russia centred on waste recycling.

Llewellyn: A widely-travelled businessman

The Russian media christened him the "garbage king" and alleged that he had a criminal record and was arrested in 1997 for improper business practices.

Mr Llewellyn admitted he was arrested in the US but said all charges were dismissed.

"These accusations certainly did have an effect on negotiations," said spokesman for the Mir space station, Sergei Gorbunov.

Energia have been desperate to raise private money to keep Mir in space ever since the Russian government announced it was withdrawing state funding.

Mir's coming down

However, the Russian Space Agency Director, Boris Ostrumov, admitted on Wednesday that it was impractical to keep Mir flying in the face of the Russian space programme's chronic under-financing.

He said Russia would instead place priority on shared projects like the upcoming International Space Station (ISS). This will have come as a great relief to Nasa who have long wanted the Russians to focus their resources on the ISS.

Ostorumov said that Mir will most likely stay in space until February of next year, six months after the money runs out. It will be unmanned from August, when the last cosmonauts return to Earth.

Mir has orbited the Earth for 13 years, despite originally being designed for five years' flying. Ostorumov said the station, which carries 10 tonnes of scientific equipment, was a "treasure" that would be "inexpedient" to discard.