A computer-generated image of the suicide attacker who killed five Israeli tourists and a bus driver in Bulgaria has been released by police.

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 holiday resort on July 18.

The photo was made after fingerprints and DNA samples taken from the bomber did not match with anything in international databases, said Bulgarian interior Minister Tsvetan Tsvetanov.

He said 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.

Mr 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.