The International Olympic Committee president says he has confidencethat Russian authorities will deliver a "safe and secure" Games inSochi.Thomas Bach wrote to President Vladimir Putin toexpress condolences for the "despicable" attacks that struck Volgogradwithin 24 hours, BBC reported.Investigators say the attacks on a railway station and trolleybus, which killed at least 31 people, were linked.They struck just over a month before the Winter Olympics begin.Volgograd was also targeted in October, when a suspected female suicide bomber killed six people in an attack on a bus.Itis being widely assumed in Russia that the people who carried out theVolgograd bombings were involved in the Islamist-inspired insurgencyagainst Russian rule in the Caucasus republics of Chechnya and Dagestan,and that the target was the Games, says the BBC's Moscow correspondentDaniel Sandford.In a statement, Russia's foreign ministry didnot blame any particular group but likened the attacks to acts bymilitants in the United States, Syria and elsewhere.It calledfor international solidarity in the fight against "an insidious enemythat can only be defeated together", reported Reuters news agency.Regional Governor Sergei Bozhenov said the bombings were a "serious test" for all Volgograd residents and all Russians.Russians nervousInvestigators say at least 14 people were killed in a suicide bombing on a trolleybus in Volgograd on Monday morning.Itcame a day after 17 people died in another suicide attack at thecentral station in the city. Scores were injured in the two attacks.Inhis statement, Mr Bach said he was "certain that everything will bedone to ensure the security of the athletes and all the participants ofthe Olympic Games", which open on 7 February.But correspondentssay despite intense security in Sochi, Russians are palpably nervousthat following these attacks in Volgograd - which lies 700km north-eastof Sochi - bombers could also strike elsewhere.No-one hasadmitted carrying out either bombing, but they came several months afterChechen rebel leader Doku Umarov threatened new attacks againstcivilian targets in Russia, including the Olympics.VladimirMarkin, a spokesman for the Investigative Committee - Russia's mainfederal investigating authority - said identical explosives were used inthe two attacks."This confirms the theory that the two attacks are linked. It is possible that they were prepared in the same place," he said.President Putin has ordered security measures to be tightened across Russia and in particular in Volgograd.TheUS condemned the attacks and offered its "full support to the Russiangovernment in security preparations for the Sochi Olympic Games".The UN Security Council said its members condemned "in the strongest terms" the "criminal and unjustifiable" acts.UKPrime Minister David Cameron said on Twitter he was "shocked andsaddened" by the attacks, and offered Moscow whatever help was needed.Busy marketThe latest explosion took place near a busy market in Volgograd's Dzerzhinsky district.MaksimAkhmetov, a Russian TV reporter who was at the scene of the blast, saidthe trolleybus was packed with people going to work in the morning rushhour.He described the scene as "terrible", adding that the buswas "ravaged" and that there were "bodies everywhere, blood on thesnow".Health Minister Veronika Skvortsova said the injuredinclude a pregnant woman, two 16-year-olds and a baby aged about sixmonths whose parents are assumed dead.The regional governor announced five days of mourning.The force of the explosion removed much of the bus's exterior and broke windows in nearby buildings. "Itis now possible to preliminarily say that the explosive device was setoff by a suicide bomber - a man whose body fragments have been collectedand sent for genetic testing," the Investigative Committee said in astatement.The first blast rocked Volgograd-1 station atlunchtime on Sunday, when it was packed with people travelling tocelebrate the New Year.ANN.Az