Russian security forces are studying a video posted by an Islamic militant group that claims responsibility for last month's suicide bombings in Volgograd, and threatens attacks at the upcoming Olympics in Sochi.
The video was posted online Sunday by a militant group from the predominately Muslim region of Dagestan.
In the video, two Russian-speaking men warn President Vladimir Putin to expect what they call a "present" at the Sochi Winter Olympics. The video says the two men are the suicide bombers who attacked Volgograd last month, killing 34 people. There is no independent confirmation of their claim.
In another development, hotel workers in Sochi tell reporters they have seen wanted posters for a woman from Dagestan. She is described as a 22-year-old widow of a militant killed by Russian security forces last year. The posters say the woman may be in or near Sochi and could be planning an attack.
Also Monday, Russian security forces say they killed three militants in Dagestan's capital, Makhachkala.
The deaths are the latest violence in the city. On Saturday, security forces said they killed seven suspected militants who were believed to be involved in an attack on a restaurant. That attack left at least 16 people injured.
President Putin said in comments broadcast Sunday that his country will do "whatever it takes" to ensure security at the upcoming Olympic games. He spoke about massive security preparations in and around Sochi and said: "If we betray weakness, betray fear -- display our fear -- then we will be helping terrorists achieve their goals."