SOFIA, Bulgaria (AP) -- Hezbollah was behind a bus attack that killed five Israeli tourists in Bulgaria last year, investigators said Tuesday, describing a sophisticated bombing carried out by a terrorist cell that included Canadian and Australian citizens.
The first major announcement in the investigation carried broad diplomatic implications, as countries that consider the Shiite militant group to be a terrorist organization called on Europe -- which has resisted such a move -- to crack down on the group.
Interior Minister Tsvetan Tsvetanov said two of the suspects had been living in Lebanon for years -- one with a Canadian passport and the other with an Australian one. He said investigators had traced their activities back to their home countries.
"We have well-grounded reasons to suggest that the two were members of the militant wing of Hezbollah," Tsvetanov said after a meeting of Bulgaria's National Security Council.
A third suspect entered Bulgaria with them on June 28, he said, without giving details.
Within hours, Lebanese Prime Minister Najib Mikati condemned the attack and said his country would cooperate fully.
Hezbollah, a Shiite militant group and political party in Lebanon that emerged in response to Israel's 1982 invasion, has been linked to attacks and kidnappings on Israeli and Jewish interests around the world.
The group has denied involvement in the Bulgaria bombing, and Hezbollah officials in Beirut declined further comment Tuesday. They customarily defer to Hezbollah leader Sheikh Hassan Nasrallah to comment on security issues.
The bomb exploded as the Israeli tourists made their way from the airport to their hotel in the Black Sea resort of Burgas. The blast also killed the Bulgarian driver and the suspected bomber, a tall and lanky pale-skinned man wearing a baseball cap and dressed like a tourist.
Although it was initially believed to be a suicide bombing, Europol Director Rob Wainwright told The Associated Press that investigators now believe the bomber never intended to die. He said a Europol expert who analyzed a fragment of a circuit board determined that the bomb was detonated remotely.
The investigators found no links to Iran, which Israel had accused of playing a role in the attack.
The findings increased pressure on Europe to declare Hezbollah to be a terrorist organization, as the United States and Canada do.
"The attack in Burgas was an attack on European land against a member of the European Union," Israeli Prime Minister Benjamin Netanyahu said. "We hope the Europeans learn the proper conclusions from this about the true character of Hezbollah."
U.S. counterterrorism adviser John Brennan, who is President Barack Obama's nominee to run the Central Intelligence Agency, said Europe should seek to uncover Hezbollah's infrastructure and disrupt the group's finances and operational network.
Canadian Foreign Affairs Minister John Baird went further.
"We urge the European Union and all partners who have not already done so to list Hezbollah as a terrorist entity and prosecute terrorist acts committed by this inhumane organization to the fullest possible extent," he said.
Catherine Ashton, the European Union's top foreign and security official, said the EU needs to assess the implications of the investigation seriously but stressed any decision on adding Hezbollah to the EU list of terrorist organizations would require a unanimous decision by the foreign ministers of the 27 EU countries. Their next scheduled meeting is Feb. 18.
France and Germany, wary of coming under pressure to condemn the group, had urged investigators not to publicly name Hezbollah in the bombing, according to a U.S. official who spoke on condition of anonymity because he was not authorized to speak to the news media.
Wainwright -- whose organization helps coordinate national police across the EU, which includes Bulgaria -- said in an interview that counterfeit U.S. driver's licenses that were found near the bombing scene were made in Lebanon. Tsvetanov said the fake licenses were from Michigan.
The investigators, he said, found no direct links to Iran or to any al-Qaida-affiliated terror group.
"The Bulgarian authorities are making quite a strong assumption that this is the work of Hezbollah," Wainwright said. "From what I've seen of the case -- from the very strong, obvious links to Lebanon, from the modus operandi of the terrorist attack and from other intelligence that we see -- I think that is a reasonable assumption."
For Hezbollah, the accusation comes at a horrible time.
Despite its formidable weapons arsenal and political clout in Lebanon, the group's credibility and maneuvering space has been reduced in recent years, largely because of the war in neighboring Syria but also because of unprecedented challenges at home.
Hezbollah still suffers from the fallout of a month-long 2006 war with Israel, in which it was blamed by many in the country for provoking an unnecessary conflict by kidnapping soldiers from the border area.
Since then, the group has come under increasing pressure at home to disarm, leading to sectarian tensions between Lebanese Shiite Hezbollah supporters and Sunni supporters from the opposing camp that have often spilled into deadly street fighting.
More recently, Hezbollah's support for the government of Syrian President Bashar Assad has proved costly to its reputation, and last week Israeli warplanes bombed what was believed to be a shipment of sophisticated anti-aircraft missiles headed to Hezbollah.
New troubles for Hezbollah could also add to Iran's international isolation. The Iranian regime is already under international sanctions for its suspect nuclear program, and has seen its position weaken due to its close ties with the Syrian regime. Its association with Hezbollah will likely further hurt Iran's international image.
Wainwright warned the attack is an indication of a real threat to Israelis and Jews in Europe.
"Even if it's not Hezbollah, it has still obviously been carried out by an organization with some capability in the world, so the threat remains," Wainwright said. "I don't want to exaggerate the scale of that threat, but I think law enforcement authorities -- government authorities -- should take notice of this incident and prepare for the possibility at least of similar attacks in Europe."
Matt Lee in Washington; Josef Federman in Jerusalem, Bassem Mroue and Zeina Karam in Beirut, Lebanon, Don Melvin in Brussels, and Rob Gillies contributed to this report.