Unprecedented security measures have been taken in Russia’s southern city of Vladikavkaz in North Ossetia after 12 people were killed and dozens injured in an apparent suicide bombing. The incident occurred just a month after a deadly car bomb attack in t

President Medvedev has demanded that the prosecutor's office thoroughly investigate the case.

Police say the blast was a terror attack as traces of explosives were found nearby.

All the victims are reportedly residents of North Ossetia. Five of those killed in the blast have been identified by the North Ossetian Ministry of Internal Affairs as three women and two young men aged 17 and 22. Thirty-nine people who were injured and are now in hospital have also been identified.

Boris Digurov, the head doctor of a hospital in Vladikavkaz, said that two of the injured are in a very bad condition. He added that most of those hit by the blast were young people around 17-18 years old, many of whom were students at nearby universities.

The severed head of a suspected suicide bomber was found at the scene.

The blast reportedly had a force of around 300-500g of TNT equivalent, with a radius estimated at 150 metres.

The explosion is said to have occurred outside the minibus rather than inside, as there was no sign of explosives anywhere in the vehicle.

The North Ossetian authorities have declared that Saturday, November 8, will be a day of mourning. Security has been stepped up in North Ossetia.

The American embassy in Moscow has condemned the violence. U.S. ambassador John Beyrle expressed his condolences to the families of the victims. He added that the U.S. will continue together with Russia to make every effort to destroy any terrorist groups. The U.S. is the only country so far to have reacted to the events.

Vladikavkaz is the capital of North Ossetia. Refugees from South Ossetia fled to the city during the August conflict between Russia and Georgia.

The attack is just one of a number of deadly explosions in the Caucasus region since the end of the military confrontation.

Last month seven peacekeepers were killed in Tskhinval. South Ossetian authorities accused Georgia of organising terrorist acts on it territory.

There were also reports of planned attacks by Georgian radicals in Moscow.