Kremlin vows to punish those behind blast

Russian President Dmitry Medvedev vowed to track down and punish those behind a suicide bomb attack which killed at least 31 people and injured over 100 others at Russia's biggest airport.

"Security will be strengthened at large transport hubs," Medvedev wrote on Twitter.

"We mourn the victims of the terrorist attack at Domodedovo airport. The organisers will be tracked down and punished," he said.