MOSCOW: Explosions detonated by two female suicide bombers killed at least 37 people and injured dozens more on two packed Moscow metro trains in the morning rush hour on Monday, officials said.
It was the worst attack in the Russian capital for six years.
President Dmitry Medvedev said that Russia will fight terror without hesitation and to the end, ordering security to be stepped up on transport across the country.
"The policy to suppress terrorism in our country and the fight with terrorism will be continued," Russian news agencies quoted Medvedev as telling an emergency meeting convened after the twin blasts.
"We will continue the operation against terrorists without hesitation and until the end," he added.
Prime Minister Vladimir Putin said that the "terrorists" responsible for the twin suicide bomb attacks in the Moscow metro will be caught and "destroyed."
"I am sure that law enforcement agencies will do everything to find and punish the criminals" who carried out the attack, Russian news agencies quoted Putin as saying during a visit to the Siberian city of Krasnoyarsk.
No group immediately claimed responsibility for the blasts but suspicion fell on groups from Russia's North Caucasus, where the Kremlin is fighting a growing Islamist insurgency.
But the head of the Federal Security Service, Alexander Bortnikov, said the two suicide bombers were likely from Russia's mainly Muslim North Caucasus region.
The first blast tore through the second carriage of a train as it stood at the Lubyanka metro station, close to the headquarters of Russia's main domestic security service (FSB), at 0756 (0356 GMT), killing 25 people.
Another blast wrecked the second carriage of a train waiting at the Park Kultury metro station at 0837 (0437 GMT), killing 12 more people, an Emergencies Ministry spokeswoman said.
"The blast hit the second carriage of a metro train that stopped at Lubyanka, at 0756 (0356 GMT)," ministry spokeswoman Irina Andrianova told Reuters.
She said there were killed both inside the carriage and on the platform. The stations were packed with rush hour commuters.
"Two female terrorist suicide bombers carried out these bombings," Moscow Mayor Yuri Luzhkov told reporters at Park Kultury metro station.
Surveillance camera footage posted on the Internet showed bodies lying in Lubyanka station lobby and emergency workers treating victims.
The current death toll makes it the worst attack on Moscow since February 2004, when a suicide bombing killed at least 39 people and wounded more than 100 on a metro train.
Chechen separatists were blamed for that attack.
