Putin vows revenge for Moscow airport bombing

Lax security also was blamed for Monday's explosion in the international arrivals area of Domodedovo Airport that also injured 180 people, with President Dmitry Medvedev criticising police and managers at the airport, the largest of three that serve the capital.

NTV television showed a photograph of what it said was the detached head of the suspected bomber. Investigators have said that DNA testing will be necessary before the man, who appears to be in his 30s, can be identified. A two-second video of the blast itself, broadcast on state television and said to be from a closed-circuit TV camera, showed a burst of flames and passengers falling and fleeing as smoke filled the hall.

No one has claimed responsibility for the attack, but suspicion has fallen on Islamist separatists from Chechnya or elsewhere in the restive Caucasus region who have been battling Russian authority for over 15 years. Chechen insurgents have claimed responsibility for an array of attacks, including a double suicide bombing on Moscow's subway system last year that killed 40 people. They also have used Domodedovo Airport before, with two suicide bombers slipping through its security in 2004 to kill 90 people aboard flights that took off from there.

Putin rose to power in 2000 on a now-famous vow that Chechen rebels would be hunted down and killed "in the outhouse." But despite a second devastating war that brought Chechnya back under Moscow's control and sanctioning the violent rule of his chosen Chechen leader, Putin has been unable to wipe out the Islamic insurgency that has spread across much of the Caucasus.

A brutal crackdown on the insurgency has produced a backlash that has led to almost daily attacks on police and security forces in the Caucasus and brought the terror to Moscow. Muscovites have also seen a sharp rise in ethnic tensions between Slavic Russians and Muslims from the Caucasus, many of whom come to the capital in search of work.