Russian state investigators have said they will look into a request from politicians to investigate what they called the "organisation, financing and conduct of terrorist acts" by the US and other Western countries.
The director of Russia's FSB security agency said yesterday that he believed Ukraine was involved in the terror attack on a concert hall near Moscow, and that the US and UK had helped.
The West says it has intelligence the attack was carried out by Islamic State affiliate ISIS-K.
Islamic State also claimed responsibility for the attack.
Lord Cameron, the UK foreign secretary, posted on X yesterday: "Russia's claims about the West and Ukraine on the Crocus City Hall attack are utter nonsense."