0120 GMT June 20, 2019
Badreddine, 55, was one of the highest ranking officials in the group, and was believed by the US government to be responsible for Hezbollah's military operations in Syria, where, alongside Syrian forces, it is fighting the terrorists, Reuters reported.
Badreddine was a brother-in-law of late Hezbollah military commander Imad Moughniyah.
Iranian Foreign Minister Mohammad Javad Zarif said on Friday the martyrdom of Hezbollah's military chief will certainly strengthen the Hezbollah’s determination to fight the Israeli regime and terrorism, Press TV reported.
In a message to Hezbollah Secretary General Sayyed Hassan Nasrallah, Zarif expressed the Islamic Republic's condolences on the martyrdom of Mustafa Badreddine by the Israeli regime.
The Iranian minister said Badreddine was "all passion and devotion" in defending the ideals of Islam and the resistant Lebanese people and in fighting terrorism.
At least four prominent figures in Hezbollah have been martyred since January 2015.
Hezbollah said Badreddine had been martyred in a big explosion targeting one of its bases near Damascus airport.
Nawar al-Saheli, a Hezbollah member of Lebanon's Parliament, said Israel was behind the killing.
"This is an open war and we should not preempt the investigation but certainly Israel is behind this," he told the Al-Manar TV station. "The resistance will carry out its duties at the appropriate time."
The Lebanese TV station Al-Mayadeen reported Badreddine had been martyred in an attack by Israel, which has struck Hezbollah targets in Syria several times since the conflict began in 2011.
There was no immediate response from Israel.
Hezbollah, a political and military movement which is Lebanon's most powerful group, has grown stronger since forcing Israel to end its 22-year occupation of southern Lebanon in 2000. The sides fought a 33-day war in 2006, their last major conflict.
When asked by an interviewer on Israel Radio about possible Israeli involvement, cabinet minister Zeev Elkin, a confidant of Prime Minister Benjamin Netanyahu, declined to comment.
For years, Badreddine masterminded military defense of Lebanon against Israeli invasions and managed to escape kidnap by Arab and Western governments.