Russia, which is set to hold a monopoly on flights to the international space station (ISS), wants to charge more for rides on its Soyuz rocket, the space agency head said Tuesday.

"At a meeting of the space agency chiefs in Tokyo, I want to discuss the maintenance of transport to the station," Roskomos head Anatoly Perminov was quoted by the Interfax news agency as saying.

"We have an agreement until 2012 that Russia will be responsible for this. But after that? Excuse me but the prices should be absolutely different then!"

When NASA retires its long-serving shuttle fleet as planned later this year, the United States and other countries will be wholly dependent on Russia to fly the station's six-man crew to and from orbit.

NASA has signed a deal worth 306 million dollars (224 million euros) with Roskomos for six rides to the ISS in 2012 and 2013, or a charge of 51 million dollars per US astronaut.

But with space now limited aboard the Soyuz rocket, Russia looks set to curb its lucrative space tourism service, for which it had charged cosmos-crazed tycoons 35 million dollars (28 million euros) for the ultimate adventure.

The floating ISS research station was to be closed in 2015 and ditched in ocean like its predecessor the Russian Mir station, but the 16 countries involved are in talks to extend the station's life to 2020.