MOSCOW: Two female suicide bombers blew themselves up on packed metro trains in Moscow's morning rush hour Monday, killing at least 36 people at stations close to the ex-KGB headquarters and Gorky Park.

President Dmitry Medvedev vowed that Russia would fight terror "until the end" after the apparently coordinated blasts brought suicide bombings back to the city with a vengeance after a lull over the last half decade.

The first explosion struck just before 7:57 am (0357 GMT) on a train that had stopped in the Lubyanka station just below the headquarters of Russia's FSB security service, the former KGB.

About half an hour later, a second explosion went off in a carriage of a train on the platform at the Park Kultury metro station, also in central Moscow and named after the iconic Gorky Park that lies over the river.

The investigative committee of prosecutors said the blast at the Lubyanka station killed 24 people and wounded 17. The second at Park Kultury left 12 dead and 15 wounded.

Moscow authorities said the attacks were carried out by female suicide bombers wearing belts packed with explosives.

He said the force of the blasts had an equivalent of about three kilograms (6.6 pounds) of TNT explosives each.