At the moment, no programme for its use nor any funding has been put in place to support the platform beyond 2015.
But the European Space Agency’s (Esa) Director General, Jean-Jacques Dordain, told the BBC the uncertainty was undermining best use of the ISS.
He said he was persuaded of its worth, and expressed the desire to keep flying the station until at least 2020.
Only by guaranteeing longevity would more scientists come forward to run experiments on the orbiting laboratory, he argued.
“I am convinced that stopping the station in 2015 would be a mistake because we cannot attract the best scientists if we are telling them today ‘you are welcome on the space station but you’d better be quick because in 2015 we close the shop’,” he said.