Three potential female suicide bombers - one of whom is believed to be in Sochi where the Winter Olympics begin next month - are being hunted by Russian security officials .
Russian police warned that Ruzanna Ibragimova, 22-year-old widow of a dead Islamic militant, is at large in Sochi.
Authorities in Russia have blamed the so-called "black widows" of killed insurgents for previous suicide attacks in the country.
Sochi, a Black Sea resort town, will host the games next month amid concerns about security and potential terrorist attacks.
Police leaflets seen by a reporter at a central Sochi hotel contained warnings about the three women.
They included pictures of the two other women in veils, 26-year-old Zaira Aliyeva and 34-year-old Dzhannet Tsakhayeva. The leaflets said they had been trained "to perpetrate acts of terrorism".
It warned that the two women "are probably among us", but, unlike Ibragimova's case, did not say if they were in Sochi.
The Olympics are to be held from February 7 to 23. Russia has mounted an intense security operation in the city, but concern persists that "soft targets" outside the Olympic venues, such as buses and tourist facilities, are vulnerable to attack.