Funerals are being held in Russia for the victims of a double-suicide bombing on the Moscow metro that killed 39 people on Monday.
Chechen rebel leader Doku Umarov has claimed responsibility for the bombings. In a video posted on an Islamic rebel website, Umarov said he had personally ordered the bombings and said attacks on Russia would continue.
One of the metro stations bombed was just metres from the headquarters of Russia's Federal Security Service, the country's main domestic security service.
On Wednesday, 12 people were killed by twin suicide bombings targeting police in Russia's North Caucasus republic of Dagestan.
Reports from Dagestan say two people died after a blast ripped through their explosives-laden car. It follows the deaths of at least 12 people in suicide bombings in the Dagestani town of Kizlyar.
Prime Minister Vladimir Putin has called on the security forces to "scrape from the sewers" those responsible for the Moscow attacks.
At a government meeting following the bombings in Dagestan, Mr Putin condemned the "terrorist act" and said he did "not rule out that it is one and the same gang at work".
President Dmitry Medvedev said the two sets of bombings were "links of the same chain".