Bulgarian authorities are on the trail of two men they believe to be linked to a deadly bombing attack that targeted a bus carrying Israeli tourists in the eastern Bulgarian city of Burgas this time last year.

The Bulgarian Ministry of Interior today released images of men they identified as Meliad Farah, an Australian national also known as Hussein Hussein, and Hassan el Hajj Hassan, a Canadian national. A statement accompanying the pictures from the ministry said the men are "suspected of having [a] link with the bombing" and said the pair was believed to be traveling in Bulgaria under false names like Brian Jeremiah Jameson, Jacque Felipe Martin and Ralph William Rico.

Five Israelis and one Bulgarian were killed when a suicide bomber detonated explosives aboard a bus in Burgas, a tourist hub on the Black Sea, on July 18, 2012. Top Israeli officials, including Prime Minister Benjamin Netanyahu, immediately suspected Iran of directing the attack through the Lebanese militant group Hezbollah. In February, Bulgaria's then-interior minister, Tsvetan Tsvetanov, said authorities found it was a "reasonable assumption" that two suspects they had identified in connection with the bombing - an Australian and a Canadian - were members of Hezbollah. Today's statement made no mention of the Hezbollah connection.

Farah and El Hajj Hassan are common last names in Lebanon. Scores of Lebanese emigrated to Canada and Australia during the Middle Eastern nation's 15-year civil conflict beginning in the mid-1970s.

Iranian authorities "vehemently rejected" the accusation they were involved in the bombing and instead claimed that Israel was likely behind the attack on its own citizens, Iran's semi-official Press TV reported in August 2012. Hezbollah also previously denied culpability.

This week Hezbollah's military arm was officially designated a terrorist organization by the European Union following concerns over the role it is allegedly playing in Syria's civil war. The U.S. State Department designated Hezbollah a terrorist organization in 1997.

The Burgas bombing was cited by British officials in their case for the EU's blacklisting of the Lebanese group. The new EU designation curtails the group's financial capabilities by freezing any assets it holds in the 28 nations that make up the EU zone.