Russian state investigators said on Wednesday they would study a request from parliamentarians to investigate what they called the "organization, financing, and conduct of terrorist acts" against Russia by the United States and other Western countries.
The director of Russia's FSB security agency said on Tuesday that he believed Ukraine, along with the United States and Britain, were involved in an attack on a concert hall just outside Moscow that killed at least 139 people.
British Foreign Secretary David Cameron posted on X: "Russia’s claims about the West and Ukraine on the Crocus City Hall attack are utter nonsense."
Islamic State took responsibility for the Moscow shooting. Washington and Paris have said they have intelligence confirming the Islamist militant group was behind the attack.