"We think they can afford it," the diplomat said on condition of anonymity.

Russia has called for extra US funding after the United States ground its fleet following the February 1 Columbia space shuttle disaster, leaving Russia the only one capable of servicing the ISS.

The United States has said it would not provide funding because of a US law that prohibits financial aid to Russia because of its cooperation with Iran's nuclear program.

The diplomat said Washington would not consider lifting the law "while the Iran situation is not getting better, but worse."

Earlier this month, Russian President Vladimir Putin said he would consider providing extra funding for the rotating space station, a 16-nation project in which Moscow and Washington are the main participants.

A new two-man crew was due to blast off Saturday from the Baikonur cosmodrome in Kazakhstan for the ISS -- replacing the crew that has been aboard the station since before the Columbia exploded upon re-entry, killing seven astronauts.

The disaster put the very fate of the International Space Station in question, and the heads of the Russian and US space agencies are due to meet in Moscow on May 5 to discuss its future, Russian space chief Yury Koptev said, quoted by ITAR-TASS news agency.

"We intend to discuss a program of further financing for the ISS, as part of a joint plan between the United States and Russia for mutual cooperation in the space sphere," he said.

SPACE.WIRE