Specialists from the Organization for the Prohibition of Chemical Weapons (OPCW) carried out an inspection at an undisclosed location in Russia last week, the Russian Defense Ministry's official publication has said.
It was not clear whether the inspection was connected to the nerve-agent poisoning in Britain of former Russian double agent Sergei Skripal and his daughter, Yulia, but Reuters quoted a diplomatic source as saying that that was unlikely.
On its website, the newspaper Krasnaya Zvezda on April 6 published a graphic showing military-related events over the past week that included a mention of two military inspections by "foreign specialists on the territory of Russian Federation."
One of them was conducted by an "inspection group of the Technical Secretariat of the OPCW," it said.
The website didn't provide any further details, and Defense Ministry officials have not commented.
Reuters quoted a source who spoke on condition of anonymity because of OPCW confidentiality rules as saying that "it must have been related to a regular inspection" of a chemical-industry site.
In 2017, Russia said that it completed the destruction of some 40,000 tons of chemical weapons that it had declared to the global chemical-weapons watchdog.
The OPCW has been involved in the probe into the poisoning of Sergei and Yulia Skripal, who were found slumped on a bench in the English city of Salisbury on March 4 and remain hospitalized.
Britain accuses Russia of poisoning the pair with a military-grade nerve toxin. Russia denies involvement, and the dispute has dramatically deepened tensions between Moscow and the West.
A British court gave OPCW specialists blood samples taken from Sergei and Yulia Skripal for tests, and the agency is also checking the toxin used in the attack.
Russia wants to be involved in investigations into the poisoning, but its call for a joint probe failed when it was outvoted at an emergency OPCW meeting on April 4.
Sergei Skripal, a former colonel in Russia's military intelligence agency, was convicted of treason in 2006 by a Russian court that ruled he spied for Britain.
Russia released him from prison in 2010, in a spy swap involving the United States, and he moved to Britain.