Bulgaria will reportedly blame Iran and Hezbollah on Tuesday for a bombing that claimed the lives of five Israelis and a Bulgarian over the summer. An Australian is also suspected in the bus attack.

Sofia has been mum thus far on placing blame for the July 18 attack on a bus at the Burgas airport, though Israel publicly pointed its finger at Hezbollah and its patron Iran immediately after the attack.

The interior minister of Bulgaria is expected to brief top officials on the investigation into the bombing thus far and announce the findings of the probe, which has yet to produce any arrests, later Tuesday.

Two Western officials told the Associated Press an Australian is a suspect in the bus attack.

The officials are familiar with the investigation and spoke Tuesday only on condition of anonymity because they are not authorized to speak to the news media.

The Wall Street Journal, citing US and European officials briefed on the report, said Lebanese Shi’ite terror group Hezbollah would take the brunt of the blame, along with Iran, which will be accused of ordering the attack.

Five Israeli tourists and a Bulgarian bus driver were killed in the bus bombing at the airport outside the popular Black Sea resort town of Burgas, and another 30 people were injured.

The anticipated report may push the European Union to designate Hezbollah as a terror organization — something Israel and the United States have urged. European heavyweights Germany and France have not designated Hezbollah as a terror group.

Naming Hezbollah a terror organization could have far-reaching political ramifications that officials fear would disturb Lebanon’s fragile peace and cause confrontations between the EU and Syria and Lebanon, the Wall Street Journal reported. The EU would also need to reevaluate its relatively open-door policy for Hezbollah’s members and funds via the continent.

The US and Israel accused Iran’s Islamic Revolutionary Guards of masterminding a string of terror attacks aimed at Israeli and American nationals in India, Thailand, and Georgia over the past two years. Iran and Hezbollah denied any involvement in those attacks — which were speculated to be retaliations for what Tehran claimed was Israel’s assassinations of leading Iranian nuclear scientists.

Bulgaria’s Interior Minister Tsvetan Tsvetanov was set to announce the results of the interim progress report of the attack Tuesday after a high-level security meeting between the prime minister, top cabinet members and military officials. It was not yet clear if the report would reveal which individuals were behind the terror attack. The White House was also expected to issue a statement after the release of the report.

Last month, the lead investigator in the case was dismissed after she told a Bulgarian newspaper that all three suspects were foreigners, with no local accomplices. The investigator, Stanelia Karadzhova, told Bulgaria’s 24 Chasa daily that one of the suspects had been identified and that an arrest warrant had been issued.

Karadzhova said new evidence suggested the bombing was not intended to be a suicide attack, as previously believed. Karadzhova said the bomber either pushed the detonator by mistake, or that somebody triggered the explosives remotely.

This image taken from security video provided by the Bulgarian Interior Ministry on Thursday, July 19, 2012, purports to show the unidentified bomber, center, with long hair and wearing a baseball cap, at Burgas Airport in Burgas, Bulgaria, on Wednesday, July 18, 2012. (photo credit: Bulgarian Interior Ministry/AP)

This image taken from security video provided by the Bulgarian Interior Ministry on Thursday, July 19, 2012, purports to show the unidentified bomber, center, with long hair and wearing a baseball cap, at Burgas Airport on July 18, 2012. (photo credit: Bulgarian Interior Ministry/AP)

In December, Bulgarian Prime Minister Boyko Borisov said both he and US President Barack Obama knew who the bombers were, but more solid evidence was needed to build a case.

In January, Bulgarian police said they identified one of a trio of terrorists involved in the bombing, but that they were still searching for the suspect and did not release his name.

The suspect acted with the bomber, known under the alias Jacque Felipe Martin, as well as another accomplice, known under the alias Ralph William Rico.

The real identities of Martin and Rico had not yet been discovered, according to Bulgaria’s Sofia news agency. Investigators also suspect there may have been a fourth or fifth accomplice.

Bulgarian police have maintained all those involved were foreigners, but have not publicly said placed blame on anyone.

In November, an Interpol official said he was worried by the lack of progress in the case. Ronald Noble told Bulgarian TV the lack of progress was “abnormal.”

Dimitar Bechev, head of the Sofia office of the European Council on Foreign Relations, told the New York Times that it seemed as if Sofia had delayed naming names to avoid upsetting the EU’s relations with Hezbollah.

“If you factor in the suspicion that there are political implications beyond Bulgaria’s borders, it’s completely understandable that they’ve been playing for time,” he said.

The Associated Press contributed to this report.