A former Russian double agent received a message on his birthday saying he was on a Kremlin hit list along with Sergei Skripal, another ex-spy who was later poisoned using a nerve agent, NBC News reported.
Boris Karpichkov was warned, "be careful, look around, something is probably going to happen," he said in an interview.
He said he was told several other ex-KGB agents were on the hit list as well as Christopher Steele, the author of the dossier alleging collusion between Russia and the Trump campaign, and Bill Browder, the man responsible for a set of U.S. sanctions against Russians.
Putin has denied Russian involvement in the Skripal case, calling Britain's allegations that Russia was behind the nerve agent poisoning "nonsense." The incident has led to a major diplomatic spat between Russia and the West.