Russia on Monday likened two deadly suicide bombings in the southern city of Volgograd to attacks by militants in the United States, Syria and other countries and called for international solidarity in the fight against "terrorists".
"We will not retreat and will continue our consistent fight against an insidious enemy that can only be defeated together," the Foreign Ministry said in a statement.
It did not place direct blame on any particular group for the attacks but said they came against a backdrop of threats from militants such as Doku Umarov, leader of an Islamist insurgency in the North Caucasus who has called on fighters to prevent Russia holding the Winter Olympics in February.
This comes after a bomb blast ripped a trolleybus apart in Volgograd on Monday, killing 14 people in the second deadly attack in the southern city in two days and raising fears of further violence as Russia prepares to host the Winter Olympics.
The morning rush-hour bombing, which left mangled bodies in the street, underscored Russia's vulnerability to militant attacks less than six weeks before the Sochi 2014 Games, a prestige project for President Vladimir Putin.
Sunday's blast came less than 24 hours after a suicide bomb blast killed at least 17 people in the main railway station in the same city, a major transport hub in southern Russia.
A Reuters journalist saw the blue-and-white trolleybus reduced to a twisted, gutted carcass, its roof blown off and bodies and debris strewn across the street. Federal investigators called the blast a "terrorist act".
"For the second day, we are dying. It's a nightmare," a woman near the scene said, her voice trembling as she choked back tears. "What are we supposed to do, just walk now?"
The consecutive attacks will raise fears of a concerted campaign of violence before the Olympics, which start on Feb. 7 in Sochi, about 430 miles (690 km) southwest of Volgograd.
In a video posted on the web in July, the leader of insurgents who want to carve an Islamic state out of the North Caucasus, a string of Muslim provinces south of Volgograd, urged militants to use "maximum force" to prevent the games from being held.
"Terrorists in Volgograd aim to terrorise others around the world, making them stay away from the Sochi Olympics," said Dmitry Trenin, an analyst with the Moscow Carnegie Centre.
A female suicide bomber from the North Caucasus killed seven people on a bus in Volgograd in October.
A spokeswoman for the International Olympic Committee in Lausanne, Switzerland, said: "Our condolences go to all those affected by today's bombing in Volgograd. Unfortunately, terrorism is a global phenomenon and no region is exempt, which is why security at the Games is a top priority for the IOC. At the Olympics, security is the responsibility of the local authorities, and we have no doubt that the Russian authorities will be up to the task."
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Russian President Vladimir Putin on Monday ordered law enforcement agencies to increase security in the southern city of Volgograd and nationwide after two deadly bombings in Volgograd, the Kremlin said.
Putin issued several instructions to a committee that coordinates counter terrorism efforts "to strengthen security Russia-wide and specifically in the Volgograd region," the Kremlin said. It did not describe the instructions.
This as Russian investigators said they believe a male suicide bomber carried out an attack that killed at least 14 people on a trolleybus in the southern city of Volgograd on Monday.
"It is now possible to preliminarily say that the explosive device was set off by a suicide bomber - a man whose body fragments have been collected and sent for genetic testing," the federal Investigative Committee said in a statement.
REUTERS
For more details, please watch Dalal Abou Haydar's full report in the video above
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