Iran on Saturday called for the United Nations Security Council to meet over Israel's actions in Lebanon and across the region, Iran's U.N. ambassador Amir Saeid Iravani wrote in a letter to the 15-member body after Israel killed Hezbollah leader Sayyed Hassan Nasrallah.

"The Islamic Republic of Iran strongly warns against any attack on its diplomatic premises and representatives in violation of the foundational principle of the inviolability of diplomatic and consular premises and reiterates that it will not tolerate any repeat of such aggression," he wrote.

"Iran will not hesitate to exercise its inherent rights under international law to take every measure in defense of its vital national and security interests," Iravani said.

Israel carried out its deadly strike against Hezbollah leader Hassan Nasrallah after learning he would be meeting senior commanders in the movement's underground headquarters in southern Beirut, the Israeli military said on Saturday.

The strike, shortly after Prime Minister Benjamin Netanyahu told the United Nations General Assembly in New York that Israel would not accept Hezbollah's forces on its borders, followed the assassination of some of the group's most senior leaders over recent weeks.

Israeli military spokesperson, Lieutenant Colonel Nadav Shoshani said the operation, which the military called "New Order", occurred on Friday while Nasrallah and the Hezbollah senior chain of command were meeting to plan further attacks against Israel.

"We had real time intelligence, an opportunity, an operational opportunity that allowed us to carry out this attack," he told reporters.

Israel's Army Radio quoted the head of the air force squadron that conducted the attack as saying the pilots were only given details of the target a short time before taking off.

"The pilots did not know what the target was in the days the (strike) was being planned," the officer, identified only as Lieutenant Colonel M., was quoted as saying.

"We exposed the teams to the target only a few hours before carrying it out and they understood what they were going for."

Shoshani declined to comment on speculation that the strike may have used U.S.-made Mark 84 heavy bombs, but Brigadier General Amichai Levin, commander of Hatzerim air base, told reporters that dozens of munitions hit the target within seconds.

Ali Karaki, the head of Hezbollah's southern front, whom Israel tried to kill earlier in the week, was also killed in the raid, Shoshani said.

Hezbollah, which launched its first barrages a day after the Hamas attack on Israel on Oct. 7 last year, confirmed Nasrallah's death and said it would continue its battle against Israel "in support of Gaza and Palestine, and in defence of Lebanon".

Since then, the two sides have been exchanging daily missile and rocket fire, forcing tens of thousands of people on both sides of the border to evacuate and leaving wide areas virtually deserted.

At least six people were killed when a charter helicopter crashed in northern Pakistan on Saturday, security sources said.

The two sources, who declined to be named as they were not authorised to speak publicly, said the helicopter was chartered by a private company in northern Khyber Pakhtunkhwa province, Reuters reported.

It crashed shortly after take-off in the volatile North Waziristan area near the Afghan border.

Around 14 passengers were on board, including Russian pilots, the sources said, adding that eight people were injured in the crash and hospitalised nearby.

Pakistan's armed forces and the civilian aviation sector have suffered several air accidents in the past decade. In 2022, a military helicopter on a training exercise crashed in Khyber Pakhtunkhwa, killing both its pilots, read the report.

A Pakistan International Airlines Airbus jet crashed into a crowded residential district of the southern city of Karachi in 2020, killing most of the 99 people on board.

Iran's Supreme Leader Ayatollah Ali Khamenei has been transferred to a secure location inside the country with heightened security measures in place, two regional officials briefed by Tehran told Reuters.

The sources said Iran was in constant contact with Lebanon's Hezbollah and other regional proxy groups to determine the next step after Israel announced that it had killed Hezbollah chief Hassan Nasrallah in a strike on south Beirut on Friday.