Lebanon’s Hezbollah terrorist group says its top military commander, Mustafa Badreddine, has been killed in Syria.

Hezbollah said in a statement that Badreddine was killed in Syria, where he had been fighting extremist groups, without giving further details.

The Beirut-based Al-Mayadeen TV that is close to the group said he was killed in an Israeli air strike.

Badreddine became the group’s top military commander in 2008 after his predecessor Imad Mughniyeh was assassinated in a bomb attack in the Syrian capital of Damascus.

In the past, Israel has killed some of Hezbollah’s top commanders.

Badreddine was one of four people being tried in absentia for the murder of former Lebanese prime minister Rafik Hariri.

The 2005 suicide bombing that killed Hariri and 22 others was one of the Middle East’s most dramatic political assassinations.

The trial began last year near The Hague and is ongoing. A billionaire businessman, Hariri was Lebanon’s most prominent politician after the 15-year civil war ended in 1990.