A man arrested on suspicion of organising the St Petersburg metro bombing has denied organising the attack.
Kyrgyzstan-born Abror Azimov has appeared in court after being detained by the FSB, Russia's security service, in a Moscow suburb on Monday.
He has admitted indirect involvement in the attack but said he did not know he was taking part in terrorist activity.
The FSB say Azimov was "one of the organisers" of the attack and accused him of "training" the suspected suicide bomber 22-year-old Akbarjon Djalilov.
Djalilov, who was born in Central Asian Kyrgyzstan, is suspected to have triggered the explosive device that killed 14 people on a St Petersburg metro train on 3 April.
In court Azimov admitted indirect "involvement" in the attack.
"I did not say that I was involved in the blast", Russian news agencies quoted him as saying.
"There was some involvement by me, but not direct.
"I was given an order.
"I did not understand that I was taking part in terrorist activity."
The court has ruled Azimov can be held in detention until 3 June as the investigation into the atrocity continues.
Eight other men, all from ex-Soviet Central Asia, have also been detained in Moscow and St Petersburg in connection with the bombing.
There have been no claims of responsibility for the attack, but possible ties to Islamic State jihadists, who have threatened Russia in retaliation for its actions in Syria, are being examined.