Russia Today has posted a video clip of the interrogation of one of the suspected terrorists behind Friday's shooting spree at Crocus City concert hall near Moscow.

Earlier on Saturday, Russia's FSB security service confirmed that 11 suspects, including four of the alleged perpetrators, had been detained in Bryansk Region, not far from the Ukrainian border, RT reported.

The footage shows a bearded man lying on the ground and describing in broken Russian how he'd been paid to commit the terrorist attack.

The suspect added that he had committed the crime "for money," detailing that he had been promised 500,000 rubles ($5,418).

The alleged perpetrator claimed that half the sum had already been transferred to his debit card, the report said.