Bulgarian police on Wednesday released a computer-generated image of the suicide attacker involved in the bombing in Bulgaria that killed five Israeli tourists and a Bulgarian bus driver two weeks ago.

An illustration handout provided on Wednesday shows the suspected bomber who blew up a bus carrying Israeli tourists last month at the Bulgarian airport of Burgas. (Bulgarian Interior Ministry/Reuters)

A police statement said the image of the dark-haired man was produced after reconstructing the badly damaged face of the bomber, who was decapitated in the explosion at a popular vacation resort on July 18.

The photo was sent to partner services for possible identification after fingerprints and DNA samples taken from the bomber did not match with anything in international databases, said Interior Minister Tsvetan Tsvetanov.

He told reporters the explosives were attached to the bomber's back. Earlier reports said the bag of explosive had been placed in the luggage compartment of the bus the tourists were travelling in at Burgas airport.

Investigators, who had found only the bomber's head and limbs, were also suggesting the bomb had been attached to his torso.

Tsvetanov said that the attacker had spent "at least 20 days in Bulgaria ahead of the bombing."

Last week, Prime Minister Boiko Borisov said a sophisticated group of conspirators was involved in the bombing at the Black Sea resort town.

Israel has blamed the attack on Iran and its proxy groups, including the Lebanese militant group Hezbollah. Iran has denied responsibility, and Bulgarian authorities have not assigned blame on any particular group.