Russia on alert after second deadly suicide bombing

At least 14 people were killed today when a suicide bomber blew himself up on a packed trolleybus in Volgograd, raising new concerns about security at the Sochi Olympics a day after a deadly attack on the southern Russian city's train station.

President Vladimir Putin, under pressure to show that Russia can assure the security of tens of thousands of guests when the Winter Games open on February 7, ordered stepped up security across the country.

The twin suicide attacks on Volgograd, which until this year had no record of recent unrest, have stunned Russia and troubled the authorities as people prepare for mass New Year celebrations. At least 17 people died in yesterday's attack blamed on a suspected female suicide bomber.

The force of the blast destroyed the number 15A trolleybus, which was packed with early morning commuters and was turned into a tangle of wreckage with only its roof and front remaining.

Health ministry spokesman Oleg Salagai told Russian state television that 14 people were killed in the trolleybus bombing and 28 wounded.

Russian investigators have opened a criminal probe into a suspected act of terror as well as the illegal carrying of weapons, the Investigative Committee said.

"The explosives were detonated by a male suicide bomber, fragments of whose body have been found and taken for genetic analysis to establish his identity," said spokesman Vladimir Markin.

He said that some four kilogrammes of TNT equivalent had been used in the blast and noted the explosives were identical to those used in yesterday's train station bombing.

"This confirms the theory that the two attacks are linked. It is possible that they were prepared in the same place," he added.

The new attack will further heighten fears about security at the Winter Olympic Games in Russia's Black Sea resort of Sochi, which lies 690 kilometres southwest of Volgograd.

Putin ordered security stepped up across all of Russia after the bombings, with a special regime to be imposed in Volgograd, the national anti-terror committee announced.

Russia is already preparing to impose a "limited access" security cordon around Sochi from January 7 which will check all traffic and ban all non-resident cars from a wide area around the city.

State television said that after the latest blast in Volgograd commuters were abandoning buses and trolleybuses and going to work on foot in fear of a new attack.