The first private manned mission to the International Space Station (ISS) is set to go ahead in 2011, a US space tourism company has announced.
The mission has been agreed between the company Space Adventures and the Russian federal space agency.
A Soyuz spacecraft will be specially manufactured for this mission.
Space Adventures has so far bought seats on Soyuz missions to the ISS for five clients, with the price of a seat costing upwards of $20m (£10m).
This fully dedicated private Soyuz mission, scheduled to take place in the second half of 2011, will have two seats available in the craft for space tourists.
Earlier on Wednesday, Space Adventures announced that Google co-founder Sergey Brin had made a $5m (£2.5m) down payment to book a seat on a future orbital spaceflight.
"The Soyuz to be used for this mission shall be a specially manufactured craft, separate from the other Soyuz vehicles designated for the transportation of the ISS crews," said Alexey Krasnov from the Russian space agency, Roscosmos.
He added: "This private mission, flying two Space Adventures clients at once, will not interfere with the implementation of the ISS programme or the obligations of the Russian space agency.
"On the contrary, it will add flexibility and redundancy to our ISS transportation capabilities."
The first space tourist to fly to the ISS was Dennis Tito in 2001. Four others have followed in his footsteps: Mark Shuttleworth, Greg Olsen, Anousheh Ansari and Charles Simonyi.
The sixth client, Richard Garriott, son of Nasa astronaut Owen Garriott, is currently in cosmonaut training with his launch to the ISS scheduled for 12 October 2008.
Several other companies have also been pressing ahead with commercial space ventures.
Sir Richard Branson's Virgin Galactic business will carry six passengers on sub-orbital flights at a price of $200,000 (£100,000) per seat.
Virgin says it has sold more than 200 tickets; the first flight is scheduled for no earlier than 2009.
European aerospace contractor EADS-Astrium has announced that it is developing a four-person spacecraft to make suborbital trips.
And US space entrepreneur Elon Musk is working on a capsule that would be able to carry crew to the space station.