The Russian space agency says it will stop carrying US astronauts to the International Space Station for free.
US astronauts are currently carried by Russia for free
Agency head Anatoly Perminov said US astronauts would be ferried to the ISS "on a commercial basis" from 2006.
US shuttles remain grounded following the fatal accident last year when the Columbia shuttle burned up on re-entry.
Correspondents say that the agency, Roskosmos, operates with a budget much smaller than its US counterpart, Nasa, and is facing financial hardship.
Roskosmos has single-handedly serviced the International Space Station since the suspension of the US shuttle programme last year, Mr Perminov told Itar-Tass news agency.
It has sent two manned and five cargo spaceships to the station this year alone.
"The Russian side shouldered the entire burden... for nearly two years," he said.
"Starting from 2006, we shall bring American astronauts to the ISS on a commercial basis," he said.
He said he would visit the US early next year to put forward his proposal and to assess US progress in resuming shuttle flights in May as hoped.
The International Space Station is a collaboration between 16 nations
For 2005, Mr Perminov said, he had agreed a temporary barter scheme by which Russia pays off man-hours it owes for work on the station - a collaborative project between 16 nations - by launching US astronauts.
There has been no response yet from Nasa.
Correspondents say the Russian space agency is open about the financial hardships it faces.
It has taken two so-called space tourists into space in recent years for $20m each, and Mr Perminov said Russia was in discussions to send two more tourists in 2006.