WASHINGTON — NASA said March 28 it welcomed a Russian commitment to continue operations of the International Space Station beyond 2020, but indicated there were no firm plans to work together on a successor space station.

The agency responded to comments made by the head of Roscosmos, Igor Komarov, earlier in the day that suggested the two space agencies had not only agreed to extend operations of the ISS to 2024, but also to replace the ISS with a new station of some kind after 2024.

“Roscosmos and NASA will fulfill the program of building a future orbital station,” Komarov said at a briefing at the Baikonur Cosmodrome, as quoted by the Russian news service Sputnik.

“We will elaborate the details,” Komarov added. “It is going to be an open project, not restricted only to current participants, but open for other countries willing to join it.”

In a statement provided to SpaceNews March 28, NASA spokesman David Weaver said the agency appreciated the Russian commitment to extending the ISS, but did not confirm any plans for a future space station.

“We are pleased Roscosmos wants to continue full use of the International Space Station through 2024 — a priority of ours — and expressed interest in continuing international cooperation for human space exploration beyond that,” Weaver said.

Weaver added that the US was interested in international cooperation to support the agency’s long-term goal of human mission to Mars in the 2030s. He did not directly address Komarov’s comments, but said NASA’s current emphasis was on operations of the ISS.

“Today we remain focused on full use of our current science laboratory in orbit and research from the exciting one-year mission astronaut Scott Kelly just began, which will help prepare us for longer duration spaceflight,” he said, referring to the NASA astronaut who launched on a Soyuz from Baikonur March 27 for a one-year stay on the station.

NASA officials have recently indicated that it was unlikely that NASA would finance a replacement space station once the ISS is retired, looking instead to the private sector to develop commercial facilities that NASA, among others, could use.

“At some point this space station will wear out and there needs to be a follow-on space station,” said William Gerstenmaier, NASA associate administrator for human exploration and operations, in a speech at the Federal Aviation Administration Commercial Space Transportation Conference in February. “What we’re hoping for is that the private sector picks that up.”

Komarov’s support for an ISS extension to 2024 follows a recommendation by Roscosmos’ Scientific and Technical Council in February to continue to participate in the ISS to 2024, then separate the station’s Russian modules to form the basis of its own space station. Published accounts of Komarov’s comments did not mention those plans.