"Next year, for the first time, we will start using a crew of six members," said Alexei Krasnov, director of manned flight programs at Roscosmos.
The Kazakh National Space Agency said on Thursday that a Kazakh cosmonaut would fly to the ISS in October 2009.
Roscosmos earlier said a Russian space tourist hopeful would miss out on a trip to the ISS in the autumn of 2009, as the Kazakh cosmonaut will likely take his place.
The Russian space agency announced in 2007 that businessman and politician Vladimir Gruzdev would become the country's first Russian space tourist.
Gruzdev, a member of the ruling United Russia party, announced his plans to travel into space in April 2007. He later underwent a medical examination and was given the go-ahead to begin a space mission training program.
Boris Gryzlov, the speaker of the Russian parliament's lower house, earlier said United Russia could pay for Gruzdev's flight from party funds as a "contribution to the space program."