The US and UK have accused Russia of testing a weapon-like projectile in space that could be used to target satellites in orbit.
The US State Department described the recent use of “what would appear to be actual in-orbit anti-satellite weaponry” as concerning.
Russia’s defence ministry earlier said it was using new technology to perform checks on Russian space equipment.
The US has previously raised concerns about new Russian satellite activity.
But it is the first time the UK has made accusations about Russian test-firing in space. They come just days after an inquiry said the UK government “badly underestimated” the threat posed by Russia.
In a statement on Thursday, US Assistant Secretary of State for International Security and Non-proliferation, Christopher Ford, accused Moscow of hypocrisy after it said it wanted arms control to be extended to space.
“Moscow aims to restrict the capabilities of the United States while clearly having no intention of halting its own counter-space programme,” he said.
The head of the UK’s space directorate, Air Vice Marshal Harvey Smyth, said he was also concerned about the latest Russian satellite test, which he said had the “characteristics of a weapon”.
“Actions like this threaten the peaceful use of space and risk causing debris that could pose a threat to satellites and the space systems on which the world depends,” he said.
He urged Russia to be “responsible” and to “avoid any further such testing”.