Bulgaria is reportedly set to blame the Lebanese terror group Hezbollah for last month’s suicide bombing at Burgas airport which killed five Israelis and a Bulgarian bus driver.

Israel has long suspected the Iran-backed group of having had a hand in the July 15 bombing, which Jerusalem saw as the latest in a series of attacks and attempted attacks on Israelis around the world.

Lebanese newspaper Al-Jumhuriya reported Tuesday that Bulgarian investigators were leaning toward blaming the Lebanese group. Investigators say they are still searching for the bomber and his accomplices, and the interior minister in Sofia recently said the investigation would take a long time but was moving forward.

Hezbollah has reportedly been operating in Bulgaria for decades, and an Israeli official told the New York Times that Jerusalem picked up evidence of extensive phone traffic between Lebanon and Burgas in the months leading up to the blast.

Though the US and Israel consider Hezbollah a terror group, the EU has refused to list it as one, citing Hezbollah’s political activities in Lebanon.

Iran, which is accused of using Hezbollah as a proxy, has denied responsibility for the Burgas attack.

The bombing, which targeted a bus of Israeli tourists in the Black Sea resort town, shook tourism to the country and led to fears that more Israelis abroad would be targeted.

On Tuesday bereaved families of the five Israeli victims participated in commemorative ceremonies in Burgas. The families met with Israel envoy to Bulgaria Shaul Camisa-Raz prior to the ceremony.

The Jewish Agency announced that its fund for terror victims would give $1,500 to the family of Mustafa Kyosev, the Muslim Bulgarian bus driver killed in the bombing.

Kyosev, 36, belonged to Bulgaria’s ethnically Turkish, Muslim minority, which comprises 8% of the country’s 7 million people. He was survived by his wife Emine and 10-year-old daughter.