BY PAISLEY DODDS AND VESELIN TOSHKOV

Associated Press

SOFIA, Bulgaria

--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 announcement brought renewed pressure on the European Union from the U.S., Israel and Canada to designate the group a terrorist organization and to crack down on its fundraising operations across Europe. The EU, which regards Hezbollah as a legitimate political organization, has resisted such a move.

Interior Minister Tsvetan Tsvetanov said two of the suspects in the July 2012 attack 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.

A third suspect entered Bulgaria with them on June 28, he said, without giving details.

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 comment Tuesday.

The bomb exploded as the Israeli tourists were on their way from the airport to their hotel in the Black Sea resort of Burgas. The blast also killed a Bulgarian bus driver and the suspected bomber, a tall and lanky pale-skinned man wearing a baseball cap and dressed like a tourist.

Bulgarian investigators found no links to Iran, which Israel had accused of playing a role in the attack.

Israeli Prime Minister Benjamin Netanyahu called the investigation "further corroboration of what we have already known, that Hezbollah and its Iranian patrons are orchestrating a worldwide campaign of terror that is spanning countries and continents."

The Obama administration called on Europe to take "proactive action" to disrupt Hezbollah.

In strongly worded statements, Secretary of State John Kerry and White House counterterrorism adviser John Brennan said the Europeans, along with other countries that have balked at imposing sanctions on Hezbollah, must act to prevent additional attacks.

"We strongly urge other governments around the world--and particularly our partners in Europe--to take immediate action to crack down on Hezbollah," Kerry said. "We need to send an unequivocal message to this terrorist group that it can no longer engage in despicable actions with impunity."