President Dmitry Medvedev on Tuesday called terror the most serious threat to Russia and vowed to "liquidate" the militants behind the Moscow airport bomb blast that killed 35 people.

"Terrorism remains the main security threat to our state, the main threat to Russia and all of our cities," Medvedev said after observing a moment of silence during which he could be seen choking back tears.

"We have to do everything to make sure that the bandits who committed this crime are identified, exposed and brought to court, and the nests of these bandits, or whatever they may be called, must be liquidated," said Medvedev in televised remarks.

The Russian president also instructed his government to probe whether those responsible for ensuring the country's transportation security had properly performed their jobs.

He said the prosecutor general's office and Russia's investigative committee needed to probe "the criminal responsibility" of those who had allowed the suspected suicide bomber to walk into Domodedovo airport undetected.

"The evidence from the scene of the crime tells us that pure anarchy reigned," said Medvedev.

"People were allowed to walk in from anywhere. The entrance restriction were partial at best," he said.

He added that Russia would have to move to a system of "comprehensive checks" being practiced at Israeli and US airports.

"This is our only solution," said Medvedev. "At the same time, the level of the terror threat in Russia is higher than it is in the United States."

Medvedev also vowed  to step up security at the 2014 Winter Olympic Games in Sochi after the bloody incident.

Russian investigators linked the attack to a suicide bomber from the Northern Caucasus, a region historically plagued by Russian military campaigns.

A security source told the state-run RIA Novosti that the bomber may have been a woman, although initial reports had said it was a man in his 30s.