Russian officials say three people have been arrested in connection with the suicide bombing that killed 36 people at Moscow's Domodedovo airport last month.
Police have identified the suspected bomber as Magomed Yevloyev, 20. Officials say Magomed's sister, 16, and his brother Akhmed, 15, were arrested in Ingushetia this week along with a 23-year-old acquaintance of their brother.
Interfax reports that the three will be sent to Moscow for questioning, as the investigation into the January 24 bombing continues.
On Monday, Islamic rebel leader Doku Umarov claimed he ordered the attack, which also wounded about 150 people. Umarov made the claim in a video posted Monday on an Islamic rebel website. On the video, Umarov said he had several hundred suicide bombers prepared to carry out bombings in Moscow.
The veteran Chechen rebel commander said the attack was aimed at what he calls the "chauvinist regime" of Prime Minister Vladimir Putin.
As the self-styled "Emir" of the Caucasus, Umarov wants to set up an independent fundamentalist Islamic state in the North Caucasus, which includes the mainly Muslim republics of Chechnya, Ingushetia and Dagestan.
Some information for this report was provided by AP, AFP and Reuters.