Russia's Interfax news agency quoted an unnamed source within Russia's Roscosmos Federal Space Agency as saying an American and a Russian would take part in the one-year mission that would be twice the duration of current deployments to the ISS.
NASA responded by saying such a mission hasn't gone beyond the talking stage.
"We are exploring the idea of a one-year increment as part of preparations for exploration beyond low-Earth orbit," NASA spokesman Kelly Humphries of Johnson Space Center in Houston told SPACE.com. "But the discussion is very preliminary and no official decisions have been made."
Spending a year on the space station could give scientists an opportunity to study long-term effects of spaceflight such as would be experienced by astronauts on a mission to Mars, which would likely take two years to complete, SPACE.com said.