A month after the suicide bombing of an Israeli tourist bus in Bulgaria, investigators have made no major breakthroughs but progress has been encouraging, the country's interior minister told Agence France Presse Friday.

"It is only expected that it will take time, sometimes years, to uncover the whole mechanism behind the attack. But we are encouraged by the work we accomplished in the last 30 days," Tsvetan Tsvetanov said in an interview.

The Israeli intelligence service intercepted several telephone calls between Lebanon and Burgas in Bulgaria two months before the bombing that killed five Israeli tourists and their local bus driver, the New York Times reported on Thursday.

“The volume (of calls) intensified in the three days leading up to” the bombing, a senior Israeli government official told the newspaper on condition of anonymity.

An Israeli court charged on Wednesday several Israeli-Arab residents of Nazareth and Ghajar for allegedly helping Hizbullah transfer explosives to Israel, the Jerusalem post reported.

The Nazareth District Court charged the men with assisting in the infiltration of the 20 kilograms of C4 explosives on June 5, it said.

The deadly bomb attack on Israeli tourists last month at Bulgaria's Burgas airport was planned abroad, but the explosive device was likely made in Bulgaria, a top interior ministry official said Saturday.

"I can definitely say that the attack was plotted, prepared and implemented by people who are very far away from Bulgaria," ministry chief of staff Kalin Georgiev told the 24 Hours newspaper in an interview.

More than two weeks since a deadly bombing on a bus carrying Israeli tourists in Bulgaria, investigators have still not identified the young perpetrator or his suspected accomplices.

Police have the fingerprints and DNA of the bomber, who killed five Israelis and the Bulgarian bus driver as well as himself in the July 18 attack at Burgas airport, but they have drawn a blank on international databases.

Interpol has distributed a computer-generated image of the suspected suicide bomber who killed six people in an attack in Bulgaria last month.

The global policing body said Thursday it had issued a Black Notice -- used to seek information on unidentified corpses -- to its 190 member countries urging them to make the image public in the hopes of identifying the suspect.

Bulgarian police on Wednesday released a composite picture of the man they think blew himself up on a bus packed with Israelis, killing six people last month in the Black Sea resort of Burgas.

The computer-generated picture shows a young man with fair skin, light-colored eyes, a high forehead and short dark brown hair.

Iran is the "pre-eminent" state sponsor of terrorism and together with Hizbullah are pursuing increasingly destabilizing activities around the world since the 1990s, the U.S. State Department's counterterrorism coordinator, Daniel Benjamin, said Tuesday.

“Iran is and remains the preeminent state sponsor of terrorism in the world … and also, together with Hizbullah, as they pursue destabilizing activities around the globe, we are firmly committed to working with partners and allies to counter and disrupt Iranian activities,” Benjamin told journalists after a briefing on the annual "Country Reports on Terrorism."

Bulgarian Tourism Minister Delian Dobrev said on Tuesday forensic experts were close to producing an image of the suicide bomber who killed six people in an attack on Israelis at a Black Sea resort.

"The investigation into the attack is making progress and we have succeeded in recreating 95 percent of the face of the murderer," Israeli President Shimon Peres' office quoted Dobrev as telling his host during a meeting in Jerusalem.

Iran's U.N. envoy on Wednesday accused Israel of staging a suicide bomb attack on an Israeli tourist bus in Bulgaria.

The envoy Mohammad Khazaee said Israel staged the attack, in which five Israelis and their Bulgarian driver were killed, as part of a campaign of "state terrorism operations and assassinations aimed at implicating others for narrow political gains."