Moscow said on Wednesday it had denied a visa for a candidate to head the mission of US space agency NASA in Russia, in what it described as retaliation for the US denial of a visa to an undisclosed Russian official.
Russia did not identify the US official who had been denied a visa, or provide further details of the incident for which it was retaliating. The US embassy did not immediately respond to a request for comment.
"It was a reciprocal step," RIA state news agency quoted Deputy Foreign Minister Sergei Ryabkov as saying.
Russia and the United States have cooperated closely in space exploration for decades, jointly flying the International Space Station, despite deteriorating relations in other areas.
Ryabkov said NASA was not responsible for creating obstacles that thwarted interaction with Moscow, but that this was not the case for other US government bodies.
"Ideally we would eliminate" restrictions on diplomatic visas between the two countries, he said. "We will propose this to the administration in Washington."