The National Anti-terror Committee, part of the FSB security service, said that eight suspects were detained in a house in Makhachkala, capital of Dagestan.
Four of the six detained women, who were aged between 15 and 29, were the widows of rebels killed by the authorities.
“Officers seized the detained suspects “farewell” (?) letters to their families, expressing their wish to end their life and advising their “sisters” to follow suit,” it said.