Moscow bombing: Medvedev in Domodedovo airport pledge
President Dmitry Medvedev has vowed to track down and punish those behind an apparent suicide bomb attack at Moscow's Domodedovo airport that killed 35 people and injured more than 100.
He also said "there were clear security breaches" at the airport, which allowed Monday's bombing of the international arrivals terminal.
Unnamed officials said three suspects were being sought over the attack.
Suspicion has fallen on Russia's restive North Caucasus region.
Last March the Russian capital's underground system was rocked by two female suicide bombers from Russia's volatile Dagestan region, who detonated their explosives on the busy metro system during rush hour, killing 40 people and injuring more than 80.
Militant groups fighting in the Caucasus know how important the perception that the president and prime minister provide a secure society is, and to undermine that is a key aim, analysts say.
Police sources have hinted that the Domodedovo airport bombing may be linked to Russia's most volatile region.
Thick drops of blood
Monday's explosion rocked the airport's busy international arrivals hall, where friends and drivers meet passengers who have passed through customs.
Eyewitnesses told Russian TV that before a bomber detonated the equivalent of 7kg (15lb) of TNT, he had shouted: "I'll kill you all!"
Scenes of panic ensued as the area filled with smoke, with bodies strewn across the floor.
One Briton was among the dead.
Thick drops of blood and pieces of shrapnel were scattered across the snow-covered tarmac outside the hall, and emergency workers used luggage trolleys to ferry the dead and injured from the scene to hospitals in Moscow, 40km (25 miles) to the north-west.
Mr Medvedev has vowed a thorough investigation.
"After previous similar events, we passed appropriate legislation, and we have to check how it has been applied," he said. "Because obviously there have been lapses, and we have to get to the bottom of this."
He has admitted that poverty, corruption and conflict in the North Caucasus is Russia's biggest internal problem.
He ordered increased security across Russia's capital, its airports and other transport hubs.
But he, like Vladimir Putin before him, appears unable to find a solution that would bring stability to that region and peace to Russia, says the BBC's Steve Rosenberg in Moscow.
Mr Putin has built much of his reputation on a tough security stance to crack down on such violence.
More generally, security authorities internationally have been concerned that - while there has been a huge effort focused on airline passenger and airliner security - keeping airports and airport terminals themselves secure remains a major challenge.
The EU, US and UK were among those who condemned the attack, offering their support to the mourning Russian nation.
"We should never allow the terrorists to win," said UK Prime Minister David Cameron.