In a statement, the group said a "huge explosion targeting the group’s center near Damascus International Airport caused the death of Bader Badreddin and the injury of others," adding that an investigation on the nature of the explosion was opened, and to confirm whether the explosion was caused by an air shelling, rocket, or artillery
He was one of five figures from Hezbollah accused of the assassination of Rafic Hariri, the former prime minister of Lebanon, Digital Journal reported.
Hezbollah said in a statement that Badreddin was killed in Syria without giving further details.
Badreddin became the group’s top military commander in 2008 after his predecessor Imad Mughniyeh was assassinated in a bomb attack in the Syrian capital Damascus, Associated Press reported.
The Lebanon-based TV station al-Mayadeen earlier reported he had been killed in an Israeli attack.
There was no immediate response from Israel which has struck Hezbollah targets inside Syria several times during the country’s five-year conflict.
"We decline to comment," an Israeli military spokeswoman said, ABC News reported.
Badreddin, 55, was one of the highest ranking officials in the group, and assessed by the US government to be responsible for Hezbollah’s military operations in Syria, where it is fighting alongside Assad.
He was killed on Tuesday night, the statement said, adding that the attack targeted one of its bases near Damascus airport, Al-Jazeera reported.