Moscow, May 24 : Alexander Bortnikov, Director of Russia's Federal Security Service, on Friday said that Ukrainian military intelligence is directly involved in the terrorist attack at Crocus City Hall in the Moscow suburb.

Bortnikov made the statement at a meeting of the Council of Heads of Security Agencies and Special Services of the Commonwealth of Independent States in Bishkek, Kyrgyzstan.

He said: "The investigation is ongoing, but it is already safe to say that Ukrainian military intelligence has a direct connection to this attack."

Bortnikov promised that "all circumstances of the crime will be established and everyone involved in it will not escape punishment."

A shooting at Moscow's Crocus City Hall concert venue on March 22, followed by a massive fire, resulted in at least 144 deaths and 551 injuries, according to official statistics.

/IANS