We have some more details on the claims made by FSB security agency head Alexander Bortnikov.
The story, originally published by state news agency TASS, has Mr Bortnikov saying Western and Ukrainian services helped radical Islamists to orchestrate the attack on the Moscow concert hall.
Our team in Moscow translated his words as: “It’s possible – I think so.”
“In any case we are now talking about the facts that we have, this is general information, but there are certain developments.”
Mr Bortnikov claimed Ukraine has been trying to prove its capability, TASS reported.
“What is it expected to do to demonstrate its capability?
“It is expected to carry out sabotage and terrorist acts in the rear.
“This is what both the chiefs of Ukraine’s special services and the British special services are aiming at.
“US special services have repeatedly mentioned this, too,” he said.
Mr Bortnikov said there was a large amount of information in the public space “showing that the West and Ukraine are out to cause greater harm to our country”.
“There have been drone strikes, strikes by uncrewed boats at sea, and incursions by groups of saboteurs and terrorist organisations into our territory.”
He repeated Vladimir Putin’s claim that the attackers planned to escape across the Ukrainian border – something Kyiv has denied.
“I’ll let you in on a little secret: they were going to be greeted as heroes on the other side,” Mr Bortnikov said, according to the report.