JERUSALEM — Israeli Prime Minister Benjamin Netanyahu charged Thursday that a suicide attack against Israeli tourists in Bulgaria was orchestrated by the Iranian-backed Lebanese militia Hezbollah.
The attack Wednesday killed five Israelis, the Bulgarian bus driver, and the bomber, said Bulgarian Interior Minister Tsvetan Tsvetanov. He said investigators were using DNA to verify the identity of the bomber, who was carrying a fake Michigan driver’s license.
Bulgarian news media reported that the bomber was Mehdi Ghezali, a Swedish national and former Guantanamo Bay detainee. Ghezali was captured by US forces during a 2001 battle in Tora Bora, Afghanistan, and was released from Guantanamo in 2004.
The name of the bomber was not confirmed by Israeli or Bulgarian authorities. Video surveillance footage released Thursday by Bulgaria showed a lanky, long-haired man who wore a baseball cap, plaid shorts, and a T-shirt and blended easily into the crowd at the airport in the Black Sea resort city of Burgas.
In Washington, officials said Ghezali was a former Guantanamo detainee but could not confirm that he carried out the bombing.
Iran denied any role in the attack, the Associated Press reported. Ramin Mehmanparast, a spokesman for the Iranian Foreign Ministry, said the charges are aimed at diverting world attention from Israel’s alleged role in the assassination of at least five Iranian nuclear scientists.
The attack threatened to escalate tensions between Israel and Iran at a time when Israel is threatening military action to prevent Iran from developing nuclear weapons and international efforts to stop its alleged program are faltering.
On Thursday, Israeli officials repeated that they would retaliate swiftly and firmly, but they played down the idea that they would carry out a military strike. Analysts said they expected Israel to respond covertly, continuing its tit-for-tat clandestine war with Iran.
‘‘No option has been ruled out,’’ Israeli Deputy Foreign Minister Danny Ayalon told Israel Radio. ‘‘But the last thing that we should do is shoot from the hip. It is better to keep our cool and use our judgment.’’
The blast occurred in the late afternoon outside the airport in Burgas shortly after a charter flight carrying 154 people, all but three of them Israeli citizens, arrived from Tel Aviv, the Bulgarian Foreign Ministry said.
Israeli and Bulgarian media reported that the travelers had boarded buses that were to take them to a hotel, and the Bulgarian interior minister told Bulgarian radio that explosives had been planted on the vehicle.
On Thursday, Israeli Defense Minister Ehud Barak told Israel Radio that Hezbollah, a Lebanese Shi’ite militia, was behind the attack, and he pledged that Israel would ‘‘settle the account.’’