The agency also said it was clear the bomb targeted foreigners.

"It was no accident that the terrorist attack took place in the international arrivals zone," the state-run RIA Novosti news agency quoted Investigative Committee spokesman Vladimir Markin as saying. "Investigators believe that it was directed against, in the first place, foreign nationals."

The bomb blew up in a crowded area of the international arrivals section, killing 35 people and wounding scores more.

Markin said authorities were looking for the organizers of the attack and would not provide the bomber's name for the time being, according to RIA Novosti.

Although there has been no claim of responsibility for the bombing, suspicion has centered on the North Caucasus, where a jihadist insurgency has been fighting to establish an Islamic emirate.

While RIA Novosti did not indicate the bomber's fate, the Itar-Tass news agency indicated it was a suicide attack.

Russian President Dimitry Medvedev fired top airport security officials in the wake of the explosion, saying they had not done enough to prevent such incidents.

The bombing came less than a year after suicide bombers attacked subway stations in central Moscow during rush hour, killing nearly 40 people.