President Vladimir Putin on Wednesday called Russia's deadliest bombings in three years an "abomination" as he visited the site of two suicide strikes that killed 34 in the run-up to the Sochi Winter Olympic Games.
"The abomination of the crime that was committed here in Volgograd needs no extra commentary," Putin said during an unannounced visit to the industrial city of one million on the Volga River.
"No matter how the criminals may justify their actions, there is no justification for crimes committed against civilians, especially against women and children," the Russian leader said in televised remarks.
A bombing at the main railway station of the southern city killed 18 people on Sunday while a second strike that hit a trolleybus on Monday claimed 16 lives.
The blasts were Russia's deadliest since a suicide raid on Moscow's Domodedovo airport that was claimed by Islamic insurgents from the North Caucasus killed 37 people in January 2011.
The latest violence has laid bare the unchecked threat posed by insurgents who have vowed to target civilians in a bid to undermine Putin's preparations ahead of the Games' opening ceremony on February 7.
Putin in his first comments on the attacks on Tuesday promised to "toughly and consistently continue to fight against terrorists until their total destruction".
Investigators have opened a criminal probe into a suspected act of terror as well as the illegal carrying of weapons.
The chief spokesman for the Investigative Committee — Russia's equivalent to the US FBI — said the signature of the two bombings suggest they were plotted by the same group.
The identical makeup of the explosives "confirms the theory that the two attacks are linked. It is possible that they were prepared in the same place," Investigative Committee spokesman Vladimir Markin said.
Putin has issued a string of directives ordering security be stepped up at public transit points across the nation and extra police deployed on the streets of Volgograd.
But the same city — resting just 690 kilometres (425 miles) northeast of Sochi — was also hit by a suicide blast on a bus in October that killed six people and first alerted the authorities about the possible return of terror strikes linked to the North Caucasus that hounded Russia in the last decade.
North Caucasus guerrilla chief Doku Umarov vowed in July that his fighters would use "any means possible" to keep Putin from staging the Sochi Games.
The feared fighter — pronounced dead by Russia on repeated occasions — is seeking to carve out an Islamist republic across the North Caucasus and has claimed the region around Sochi as part of his self-proclaimed ancestral land.
The twin bombings have sparked some media speculation that Putin may take the axe against top security officials both in Volgograd and Moscow for failing to prevent more carnage less than six weeks before the Games' February 7 start.
Putin on Wednesday praised the mass security sweep that Volgograd police and interior ministry soldiers launched in the wake of the bombings.
But he also said sternly in nationally-televised comments that he would like to have a separate talk later on Wednesday with the head of Russia's powerful Federal Security Service (FSB) Alexander Bortnikov and Interior Minister Vladimir Kolokoltsev.
Putin said he wanted to be briefed personally by the two security chiefs "about the measures they were taking to improve security across the entire territory of the Russian Federation".
