Russia's FSB chief says U.S., Britain, Ukraine behind Moscow attack - TASS

The director of Russia's Federal Security Service (FSB), Alexander Bortnikov, said on Tuesday that the United States, Britain and Ukraine were behind the Moscow concert hall attack that killed at least 139 people on Friday, state news agency TASS reported.

Ukraine has denied Russian accusations of involvement in the attack, for which the Islamic State militant group claimed responsibility. Western countries have said their intelligence indicates that ISIS-K, Islamic State's Afghan offshoot, was responsible. (Writing by Felix Light; Editing by Kevin Liffey)