Chechen rebel chief Doku Umarov has claimed responsibility for last month's bombing at Moscow's main airport that killed 36 people, after an earlier warning to make 2011 a year of "blood and tears".
"This operation was carried out on my order," he said in a video posted late Monday on the Kavkaz Centre website, referring to the January 24 suicide attack at Domodedovo airport.
Umarov said he was acting in the name of Allah and the aim of the audacious attack was to set up an independent Islamic state in the North Caucasus.
He said it was also to avenge Russian "crimes" in the region and underlined that the blast was purposely staged at the international arrivals hall as the aim was to kill foreigners.
Rights activists have long criticised tactics in raids against militants in the North Caucasus -- known by the authorities as special operations -- for being overly brutal and targeting civilians as well as suspects.
Last week, the self-proclaimed leader of the so-called "Caucasus Emirate" -- which has sought to unite various groups in Russia's Caucasus and establish Islamic rule -- had vowed in a chilling video to cause mayhem in Russia this year.
In the earlier video, released late Friday on the website of the group's mouthpiece, Umarov warned Moscow: "God willing we will make this year a year of blood and tears for you."
"You better come to your senses and think," Umarov said, urging Russians to pressure their leaders into letting the region go. He said the attacks would stop after Russia withdrew from the region.
The Kremlin has repeatedly said giving up the Caucasus and negotiating with "terrorists" was not an option.
Russian security officials have said the Domodedovo airport bombing attack was carried out by a 20-year-old from one of the North Caucasus republics who was high on drugs.
A Russian security source had told Interfax news agency that the young man, Magomed Yevloyev, was the son of a school teacher and a bus driver and came from the restive Ingushetia region, bordering Chechnya.
Attacks on officials and police are a daily occurrence in the North Caucasus and after a lull of several years, suicide attacks returned to Moscow in March last year when two female suicide bombers from the region killed 40 and wounded dozens on the underground during morning rush hour.
After the March attacks Umarov said they were revenge for the deaths of innocent civilians in a Russian special operation. In a similar video at the time, Umarov said the bombings would go on as long as the "crimes committed by the gangs under (Russian Prime Minister Vladimir) Putin continued".
The Kremlin fought two wars against separatist rebels in Chechnya in the 1990s but the insurgency has now become more Islamist in tone and has spread to neighbouring regions such as Ingushetia and Dagestan.