Moscow. Russian President Vladimir Putin has vowed to fight "terrorists until their complete annihilation”, in his first comment on two suicide attacks in the southern city of Volgograd.The attacks, on Sunday and Monday, claimed a total of 34 lives.Thousands of police are patrolling public transport and checking traffic in the city following the attacks, which injured some 60 people.The first victim has been buried - a policeman killed at the station.No group has said it carried out the attacks, which Russian investigators believe are connected. They are similar to previous indiscriminate attacks by Islamist militants operating from the North Caucasus. Volgograd, a city of one million known as Stalingrad during World War II, commemorated the 70th anniversary of the battle of the same name this year, in an outpouring of Russian patriotic fervour.The bombing of railway station on Sunday and the attack on trolleybus on Monday came days before the new year holiday - one of Russia’s biggest celebrations - and just over a month before the opening of the Winter Olympics in Sochi.In a new year address in the eastern city of Khabarovsk, Mr Putin said: "We bow our heads in front of the victims of the terrible acts of terror."We will fiercely and consistently continue the fight against terrorists until their complete annihilation.”