Support offered after suicide bombs
David Cameron has offered British support to help bring to justice the perpetrators of "disgusting" suicide bomb attacks which have killed more than 30 in Volgograd.
The Prime Minister wrote to Russian president Vladimir Putin to extend his condolences for the loss of life and say the UK would do what it could to prevent further attacks.
An electric bus was targeted at rush hour, killing 14, the day after another bomber detonated a device at the city's railway station, causing 17 deaths.
Many were also injured in the attacks, which have raised concerns over the security of February's Winter Olympics, being hosted by the city of Sochi, 435 miles to the south west.
"The Prime Minister has written to president Putin to offer his condolences over the appalling loss of life in Volgograd," Downing Street said.
"The Prime Minister described the destruction of so many innocent lives as a disgusting crime and said that Britain was committed to help Russia overcome this tragedy, bring the criminals to justice and prevent any further attacks."
In a post on Twitter, Mr Cameron wrote: "I'm shocked and saddened by the Volgograd attacks. I've written to President Putin to say the UK will help Russia in whatever way we can."