Safieddine was killed in a bombing carried out by Israeli warplanes on Beirut's southern suburb, the military said in a statement on Tuesday. The attack targeted a building where, according to Israel, Hezbollah's main underground intelligence headquarters were located.

The military said that about 25 senior Hezbollah commanders were present in the building during the attack but did not clarify whether they survived, Xinhua news agency reported.

Safieddine was a cousin of former Hezbollah leader Hassan Nasrallah. After Israel assassinated Nasrallah in September, Safieddine was widely presumed to be the successor.

Safieddine was also a member of the Shura Council, Hezbollah's highest military-political body, responsible for decision-making and setting the group's policies.

"We have reached Nasrallah, his successor, and most of Hezbollah's leadership," Herzi Halevi, chief of the general staff of the Israel Defense Forces, said following the announcement of Safieddine's killing. "We will know how to reach anyone who threatens the security of Israel's citizens."

Hezbollah has not commented on the announcement by the Israeli military.