Moscow, Dec 31 (IANS): Russian experts Monday urged an upgrade of the terror prevention system after two suicide bombings hit the Volgograd city within 24 hours and left 32 killed and over 70 injured.

Russia tightened security nationwide after the attacks.

"Stopping a terrorist on the spot is not enough. A terrorist must be eliminated before leaving to carry out an attack," Xinhua reported citing Josef Linder, president of the International Counter-terror Training Association.

He believed that Volgograd was chosen by terrorists because the city was an important transportation hub and a symbol of Russian victory in World War II. "Countering terror is a continuous work. It includes infiltration of the agents into the terrorists' infrastructure."

Linder said the terrorists might be trying to create an atmosphere of panic and to trigger anti-government sentiments. "Monday's blast is literally a spit into the eyes of the authorities who just declared one day ago the 'yellow level' of emergency in the region."

However, federal authorities were certain that the twin bombings could have little impact on the upcoming Sochi Winter Olympics, over which some Western media were casting doubts.

"All necessary security measures have been taken. No additional security measures will be taken in Sochi. Everything necessary has been done," Russian Olympic Committee President Alexander Zhukov told reporters.