As the Israeli government accused Iran of standing behind Wednesday's bomb attack on Israeli tourists in Bulgaria and vowed retaliation, the relations between Israel and Iran have been put further to test.

Seven people were killed, five of them Israeli tourists, and 35 others were wounded at the Burgas airport when an as-yet unidentified man detonated a powerful charge. Israeli and Bulgarian government aircraft on Thursday flew the wounded and deceased back to Tel-Aviv.

Israel also claimed the Lebanon-based group Hizbollah, Iran's ally, was involved in the bombing.

But both Tehran and Hizbollah strongly denied the allegations, with Iranian officials calling the charge "ridiculous."

Although the blast came amid growing Iranian-Israeli tension, some believe there will probably be no major escalation of the existing rift between the two countries.

IS IRAN BEHIND THE ATTACK?

Israeli Prime Minister Benjamin Netanyahu on Wednesday accused Iran of being behind the suicide bomb attack, saying "all of the signs lead to Iran."

Israeli President Shimon Peres also mentioned Iran as his country's chief suspect on Thursday and said his country would strike "in every nest where terror operates across the world."

"As far as we are concerned, the Iranian fingerprints are clear," Yoel Mester, Counselor for Political Affairs and Press with the Mission of Israel to the EU, told Xinhua.

Mester said the terrorist attack in Bulgaria joins a long list of worldwide attacks and attempted attacks against Israeli and Western targets in recent months: in India, Azerbaijan, Thailand, Kenya, Turkey, and most recently in Cyprus.

"All of them carry the mark of Iran. It is clear that Tehran is masterminding the attacks through the Iranian Revolutionary Guards and Hizbollah," he said.

The latest attack took place exactly on the 18th anniversary of the attack on the Jewish community center AMIA in Buenos Aires on July 18, 1994, he said. Although blamed for the 1994 attack, Tehran denied any connection to it.

So far, there has been no direct evidence to support the Israeli authorities' accusation, except that the bomber was reportedly an Arab with a false American driving license.

"This could also indicate international terrorist groups behind it, because even somebody with an Arab look coming from America is unsuspicious," said Josef Janning, Director of Studies with the European Policy Center, a Brussels-based think tank.

POSSIBLE ISRAELI RESPONSE

"But if it was Iran-backed, it would be then in my view a part of the ongoing undeclared war between Israel and Iran," said Janning in an interview with Xinhua.

"Even though the Israelis do not comment on it, nor deny it, it seems fairly obvious that they are engaged in a kind of undercover war to delay or destroy the Iranian nuclear program, and it seems that they also had a role in the cyber-attacks on Iran," he added.

As Netanyahu warned on Wednesday that Israel will make a "strong response against Iranian terror," there are speculations over how far the Israeli side would go in venting their anger.

"For now, there is no clear evidence to these things, at least from the outside community," said Janning.

According to Janning, if the Israelis insist the attack was orchestrated by the Iranian authorities, they will continue their undercover war against Iran.

"We might see other moves, explosions or scientist death, car accident happening in Iran in few weeks or months. That's usually the way it works," he said.

But Janning said neither Iran nor Israel would like to see their undercover war escalate and spin out of control.

"Because all sides are conscious of the risks of escalating, that's why the war remains undeclared and undercovered," said Janning.

"That is a rather cynical match between two adversaries on a specific level, and both sides are conscious to avoid it out of hands, because they might not be able to control it," he added.