"Today I can say in all confidence that Tamerlan and Dzhokhar (Tsarnaev) are real-life devils -- complete devils," Interfax quoted Kadyrov as telling reporters in Chechnya.
"Tamerlan, thank god, was killed," he said. "Dzhokhar has been detained. Otherwise, they could have brought grief to the families of completely innocent people."
The two brothers were brought up in the former Soviet republic of Kyrgyzstan. Elder brother Tamerlan is suspected of having visited Chechnya while paying a six-month visit to southern Russia last year.
But Kadyrov -- backed strongly by the Kremlin even though he himself once fought with the rebels before switching sides -- said he had no intention of defending the Tsarnaev brothers despite their Chechen roots.
More From This Section
"I do not want to say a single word in their support," said Kadyrov.
He also suggested that any blame for the incident should be laid with the brothers' families and the countries in which they were raised.
"The parents sent them to the United States on their own -- and there is your result."
The Tsrarnaevs' parents were living in the nearby republic of Dagestan until they went into hiding after giving their one and only press conference at the end of last month.