Three potential female suicide bombers, one of whom is believed to be in Sochi, are being searched for by Russian security officials, the Associated Press reported.
Police leaflets seen by an Associated Press reporter at a central Sochi hotel on Tuesday contain warnings about three potential suicide bombers.
22-year-old Ruzanna Ibragimova, widow of an Islamic militant, was at large in Sochi, where the Winter Olympics will begin next month, a police letter said.
For previous suicide attacks in the country, Russian authorities have blamed the so-called "black widows" of slain insurgents. The term "black widow" refers to the belief that women who have carried out past suicide attacks in Russia did so to avenge the deaths of husbands or other male relatives, the AP reported.
Security officials in Sochi were not available for comment on Tuesday. The Black Sea resort town will host the games in February amid concerns about security and potential terrorist attacks, the AP reported.
Hotel staff was also distributed two other pictures of women in veils: 26-year-old Zaira Aliyeva and 34-year-old Dzhannet Tsakhayeva. It said they had been trained "to perpetrate acts of terrorism."
According to the AP, "the southern city of Volgograd was rocked by two suicide bombings in late December, which killed 34 and injured scores more. An Islamic militant group in Dagestan posted a video on Sunday claiming responsibility for the bombings and threatened to strike the games in Sochi, about 500 kilometers (300 miles) west of Dagestan."
Unlike Ibragimova, the police weren't sure if the two other women were in Sochi but warned that they "are probably among us."
No further information on the women or their motivation was disclosed, the AP reported.
Russia has mounted an intense security operation in the city for the Olympics from Feb. 7-23. Buses and tourist facilities are considered to be "soft targets" outside the Olympic venues and are seen as vulnerable to attack.