Under the deal announced Tuesday, six astronauts will be taken to the ISS through 2016 at a total cost of $424 -- $70 million per seat, compared to around $62.7 million per seat under the previous agreement that will run through 2015, SPACE.com reported.
Since the retirement of NASA's space shuttle fleet in July 2011, the space agency has been using Soyuz capsules to take its astronauts into space while it waits for U.S. firms to develop astronaut transport vehicles under its Commercial Crew Program.
Budget shortfalls have delayed those programs, with NASA now saying it will be 2017 before astronauts go into space on U.S. commercial spacecraft.
Three U.S. companies -- SpaceX, Sierra Nevada Corp. and Boeing Co. -- are working on such vehicles.
In addition to Russian cosmonauts and American astronauts, Soyuz capsules have taken astronauts from Canada, Japan and Europe to the International Space Station.