Since the United States froze all space shuttle flights following the Columbia accident in February 2003 which claimed the lives of seven astronauts, the ISS has been relying solely on Russian Soyuz spaceships for supplying it with men and freight, thus increasing the financial strain on Russia.

While the cash-strapped Russian Space Agency normally supplements its income by flying European astronauts and space tourists to the ISS, it now has much fewer opportunities to take them on board its Soyuz vessels.

"The possibilities for the Russian Space Agency to earn extra money have gone down considerably," as Russian spacecraft now have to send to the ISS Russian and US crews that used to fly on US shuttles, the Interfax news agency quoted Gorbunov as saying.

Extending manned missions to the ISS by six months following Russia's suggestion would make one seat available for a European astronaut or a space tourist on every other Soyuz flight.

Sending a space tourist to the ISS for 10 days earns the Russian Space Agency 20 million dollars (16.5 million euros), while it charges between 14.5 and 18 million dollars (12 and 15 million euros) to fly a European astronaut there for the same duration.

NASA last month postponed to March 2005 at the earliest the resumption of space shuttle launches to make further modifications to the programme.

SPACE.WIRE