Radical youth groups, either leftist or nationalist, are likely to be behind a Wednesday blast near the Federal Security Service Academy in Moscow, an unidentified law enforcement official told Interfax on Thursday.
The primitive design of the bomb, which injured no one, implies that professional terrorists, including Islamist ones, have nothing to do with the attack, the official said.
He named the People's Militia, a group headed by former intelligence Colonel Vladimir Kvachkov, as a suspect. Kvachkov was arrested in December by the FSB, which accused him of preparing a nationalist coup.
Kvachkov's lawyer denied accusations against the People's Militia. Another prominent ultranationalist leader, Dmitry Dyomushkin, said Thursday that he expected to be questioned over the blast. He also denied involvement.