The alleged perpetrator of the terrorist act in Bulgaria's Burgas might have been spotted in the capital Sofia, the Head of the Sofia Police Directorate, Chief Commissar, Valeri Yordanov, informs.

Currently, the police say they cannot confirm beyond any doubt that the man has been in Sofia, only that they have received a number of tipoffs about the perpetrator noticed in the capital.

The tipoffs were received by the Interior Ministry after the recent release of a computer-generated photograph of the man.

Any and all information is being verified and during the investigation the authorities have found people who bear a strong resemblance with the assailant, but have nothing to do with the blast, the police chief says, adding some have claimed they have spotted the man after the attack despite the firm conclusion that he died in the incident.

If the investigators establish that a certain tipoff contains viable information, it will be immediately send to the Main Directorate for Combatting Organized Crime, GDBOP, Yordanov explains.

Special security measures will be in place for the opening of the school year in the Jewish school in Sofia on September 15. There is continued increased police presence at all locations where there are Israeli citizens, in shopping malls, the subway, railroad and bus stations.

Remains of the man recovered from the scene of the fatal attack were used to create an image showing his possible appearance as part of an appeal for public assistance in identifying him.

At the request of Bulgarian police, INTERPOL issued a Black Notice – used to seek information about unidentified corpses – to each of its 190 member countries in all four official languages (Arabic, English, French and Spanish) and is now also publishing this reconstructed image to engage the public's help in identifying the man.

The July 18 terrorist attack in Bulgaria's Burgas, also known as the Burgas Bus Bombing, killed 5 Israeli tourists and a Bulgarian bus driver at the Sarafovo Airport. The initial lead, purported by Interior Minister, Tsvetan Tsvetanov, was that it has been executed by a suicide bomber, who arrived from abroad.

According to observers and terror experts, this lead is looking less and less reliable and the most viable hypothesis is that the perpetrator has been deluded, used as a mule, and has acted under the influence of illegal drugs.

Israeli media largely back the above, writing that the young man with light complexion and blue eyes had been blown remotely, while standing between two coaches with Israeli tourists. He had been unaware that he was going to die and had the task to put the explosive on one of the buses. The bomb was placed in his backpack.