At least seven tourists, including Israeli citizens, were killed in a suicide bombing of a tour bus in Burgas, Bulgaria, in July. The Israeli government accused Iran and Shiite movement Hezbollah of carrying out the attack, allegedly conducted by a man carrying a false U.S. identification card.
Bulgarian Interior Minister Tsvetan Tsvetanov said that men carrying Australian and Canadian passports were involved in the bombing.
"(There is) a well-founded assumption that they belonged to the military formation of Hezbollah," he was quoted by The New York Times as saying. "We have followed their entire activities in Australia and Canada so we have information about financing and their membership in Hezbollah."
Bulgarian officials initially suggested there wasn't enough evidence to point fingers at any organization. The government said it believed the suicide bomber didn't act alone, however.
The July 2012 attack coincided with the sixth anniversary of the Israeli conflict with Hezbollah. Iran, considered Hezbollah's regional patron, denied a role in attack and issued a statement of condemnation shortly after the incident.
Hezbollah holds political office in Lebanon but is considered a terrorist organization by some Western governments.