Deadly blast at Russia's Volgograd station

An explosion at a train station in the southern Russian city of Volgograd has killed at least 15 people, according to reports.

A female suicide bomber was thought to be responsible for the blast, Russia's anti-terrorism committee said.

Moscow is concerned militant groups could be ramping up violence in the run up to the the 2014 winter Olympic Games in Sochi.

Daniel Sandford reports.