The bomb used by terrorists to blast the trolley-bus in Volgograd was equivalent to 4 kilos of TNT, official spokesman for the Investigative Committee of Russia Vladimir Markin told Interfax on Monday.

"Early reports indicate that the explosive device was equivalent to no less than 4 kilos of TNT. It was filled with damaging agents the same as the explosive device at the [Volgograd] railway station," Markin said.

He said that similar damaging agents were used in both the Sunday and Monday explosions in Volgograd.

"As the damaging agents in the two explosive devices were identical this confirms the theory of the investigation about the connection between the two terror attacks," Markin said.

The death toll of the Volgograd trolley-bus explosion has reached 14, press secretary of the Russian Health Ministry Oleg Salagai has said.

"Unfortunately, the death toll has grown to 14," he said on Russia-24 channel on Monday.

He said that 28 more people were injured, "27 of them are in hospitals, the condition of two of them is regarded as critical."

On Sunday terrorist staged an explosion at the Volgograd railway station in which 17 people died and 45 more were injured. On Monday there was another explosion in a Volgograd trolley-bus in which 14 people died and 28 more were wounded.

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