Both my commander and flight engineer feel that we'll have a very successful flight

Dennis Tito

Nasa spokeswoman Kirsten Larson said the ISS consortium of Russia, Canada, the United States, Europe and Japan had "granted an exemption" to Mr Tito.

Agreement was finally reached on Tuesday despite initial opposition from Nasa on the grounds that Mr Tito could be a danger to his crew colleagues and to the ISS as a whole.

If all goes to plan, Mr Tito will fly into space on a Russian Soyuz mission to the ISS on Saturday, accompanied by commander Talgat Musabayev and flight engineer Yuri Baturin.

Russia had insisted that Mr Tito travel to the station no matter what. He has paid Russia $20m for the trip. Mr Tito arrived at the launch pad at Baikonur in Kazakhstan on Monday.

Safety concerns

"We will guarantee Mr Tito's safety during the flight," Russian Space Agency spokesman Sergei Gorbunov told reporters on Monday.

Mr Tito is set to become the first space tourist

A Nasa task force recommended that Mr Tito should not be allowed aboard the American portion of the space station without an astronaut escort.

The group also called for him to sleep in or near the Russian spacecraft, in case of an emergency during his sleep.

"I will be doing my own experiments, both stereo and video photography, as well as stills photography. And also hope to enjoy the beautiful view of the Earth," Mr Tito told journalists.

He and his fellow cosmonauts are due to dock with the ISS two days after launch. They will return to Earth on 5 May.

Activities curtailed

A number of experiments will be shut down or not performed during Mr Tito's stay, a Nasa official said.

The ISS crew will also halt work on the new mechanical arm installed on the space station this week. Nasa said the changes were required as "risk-mitigating actions" because of Mr Tito's presence.

The Russian space authorities have taken out a standard $100,000 dollar (�69,000) insurance policy on the lives of each of the three Soyuz crew, including Mr Tito, the Russian news agency Itar-Tass says.

The US space shuttle Endeavour is now docked with the platform and will undock on Saturday. The station's current resident crew is commanded by a Russian, Yuri Usachev.

He is accompanied by US flight engineers James Voss and Susan Helms. The trio are spending four and a half months aloft and are due to return to Earth on the Discovery shuttle in July.