BEIRUT • Lebanese Prime Minister Saad Hariri said two Israeli drones, which crashed in a suburb of Beirut dominated by the Iranian-backed Hizbollah, were designed to stir up regional tensions.
One drone fell and a second exploded before dawn and caused some damage to Hizbollah's media centre in the southern Dahiyeh suburbs, a Hizbollah official told Reuters, in the first such incident since the two sides waged war in 2006.
"The new aggression... constitutes a threat to regional stability and an attempt to push the situation towards further tension," Mr Hariri said in a statement from his office.
The Israeli military declined to comment.
A spokesman for Lebanon's Hizbollah group said Israeli drones that fell in Beirut last Saturday had certain "targets" which investigations had so far not established.
The incident took place hours after the Israeli military said its aircraft had struck Iranian forces and Shi'ite militias near Syria's capital Damascus, which it said had been planning to launch "killer drones" into Israel.
War monitor the Syrian Observatory for Human Rights said two members of Hizbollah, one Iranian and two more people of unknown identity were killed in the Israeli strikes.
Lieutenant-Colonel Jonathan Conricus, an Israeli military spokesman, told reporters "a number of attack drones", each armed with several kilograms of explosives, were to have been launched simultaneously at targets in northern Israel last Thursday but the plan was thwarted.
He did not disclose what measures Israel took that day. He described the "killer drones" - designed to slam into targets - as highly accurate. Lt-Col Conricus said the drones, accompanied by "Iranian operatives", had arrived at Damascus airport from Iran several weeks ago and were taken to a Quds-controlled compound in a village southeast of the city.
Israel carried out last Saturday's attack, Lt-Col Conricus said, after learning that another attempt to launch drones was imminent.
"Iran has no immunity anywhere. Our forces operate in every sector against the Iranian aggression," said Israeli Prime Minister Benjamin Netanyahu on Twitter. "If someone rises up to kill you, kill him first."
In Teheran, a senior Revolutionary Guards commander denied that Iranian targets had been hit in the Israeli air strikes in Syria, the semi-official ILNA news agency reported.
Israel deems Lebanon's Shi'ite Hizbollah movement as the biggest threat across its border.
They fought a month-long conflict in 2006 in which nearly 1,200 people, mostly civilians, died in Lebanon and 158 people died in Israel, mostly soldiers.
Lebanon has complained to the United Nations about Israeli planes regularly violating its airspace in recent years. Residents in Dahiyeh said they heard a blast.
A witness said the army shut the streets where a fire had started.
A Hizbollah spokesman told Lebanon's NNA news agency the second drone carried explosives, causing serious damage to the media centre. Hizbollah is now examining the first drone, he said.
Israel has grown alarmed by the rising influence of its regional foe Iran in the war in neighbouring Syria, where Teheran and Hizbollah provide military help to Damascus.
Israel says its air force has carried out hundreds of strikes in Syria against what it calls Iranian targets and arms transfers to Hizbollah.
Iran and Hizbollah are helping President Bashar al-Assad in the eight-year-old Syria war.