( CNN ) -- IOC president Thomas Bach has condemned the `` despicable attack '' on Volgograd which has raised fresh fears about security at the forthcoming Winter Olympics in Sochi . At least 31 people have been killed in two separate explosions Sunday and Monday within the space of 24 hours , with the main railway station and a trolleybus targeted . Volgograd is 690km from the Black Sea resort where the Winter Games is due to begin on February 7 , but it is a public transport hub where people traveling to Sochi by rail would likely use . Bach , set to take charge of his first Games since being elected to the top job at the International Olympic Committee in October , issued a strongly-worded statement Monday in reaction to the bombings . `` This is a despicable attack on innocent people and the entire Olympic Movement joins me in utterly condemning this cowardly act . Our thoughts are with the loved ones of the victims , '' Bach said . `` I have personally written to the President of the Russian Federation , Vladimir Putin , to express our condolences to the Russian people and our confidence in the Russian authorities to deliver safe and secure Games in Sochi . `` I am certain that everything will be done to ensure the security of the athletes and all the participants of the Olympic Games . `` Sadly terrorism is a global disease but it must never be allowed to triumph . The Olympic Games are about bringing people from all backgrounds and beliefs together to overcome our differences in a peaceful way . `` The many declarations of support and solidarity from the international community make me confident that this message of tolerance will also be delivered by the Olympic Winter Games in Sochi . '' Russian authorities have reacted to the attacks by stepping up security at major train stations and airports . No group has to date claimed responsibility for the attacks , but suspicion has fallen on Chechen separatist groups . The leader of one of the groups , Doku Umarov , has ordered rebels to target civilians outside of Russia 's North Caucasus and to disrupt the Winter Games . Sochi organizers told CNN that `` Games security is being managed by the authorities in a highly rigorous way . `` It will remain of paramount importance with an unprecedented level of planning and measures put in place over the last seven years . `` We are confident the Games in Sochi are going to be safe and comfortable for all . '' The organizing committee of the 2018 Football World Cup in Russia said it was `` constantly reviewing '' its security plans and said it was `` deeply saddened '' by the incidents in Volgograd , which is set to host matches at its 45,000 capacity Central Stadium .
CNN president Vladimir Putin condemns 'despicable ' attacks on the Russian Federation . Has written to Russian president Vladimir Putin to send condolences . Over 30 people killed in 30 attacks on public transport system . Vladimir Putin organizers remain 'confident ' about safety of athletes and spectators .