Hezbollah prepared on Monday to bury its fighters killed the day before in what it said was an Israeli airstrike in Syria as Tehran announced that an Iranian general also died with the six members of the Lebanese Shiite group.

The purported airstrike -- neither confirmed nor denied by Israel -- was a serious blow to Hezbollah, stretched thin and neck-deep in Syria's civil war where the group's Shiite fighters are battling alongside President Bashar Assad's forces, and could further ratchet up tensions in the Middle East.

Among the six fighters killed was the son of a slain Hezbollah military chief -- the group's most prominent figure to die so far in the conflict next door.

And on Monday, Tehran confirmed that an Iranian general also was killed in the Israeli airstrike Sunday in the Golan Heights. The confirmation came in a statement published on the Iranian Revolutionary Guard's website.

It said Gen. Mohammad Ali Allahdadi was on assignment in Syria, giving "crucial advice" to Syrians fighting terrorists, a reference to Sunni rebels and Islamic extremists fighting against Assad's troops. It added that Allahdadi will be buried in the coming days.

Hezbollah said its fighters were targeted as they were "inspecting positions" near the Israeli-controlled border in the Golan.

The deaths also elevated tensions between Israel and the powerful Lebanese Shiite movement, which recently boasted of rockets that can hit any part of the Jewish state. But it was also a setback for Hezbollah, coming on the heels of a confirmation last week by its leader, Sheikh Hassan Nasrallah, that the organization had uncovered and arrested a senior operative who was spying for Israel.

The burial ceremony for Jihad Mughniyeh -- the son of Imad Mughniyeh, a top Hezbollah operative assassinated in 2008 in Damascus, and one of the six Hezbollah members killed in the strike-- was to take place Monday afternoon in southern Beirut, a Hezbollah stronghold.

Iran's Foreign Minister Mohammad Javad Zarif, meanwhile, said he "vigorously condemns" the airstrike, describing it as "state terrorism" by Israel.

Jihad Mughniyeh is the most prominent Hezbollah figure killed in Syria since the Shiite militant group joined the conflict in 2012, fighting on Assad's side against the Sunni-led rebellion. The younger Mughniyeh had been photographed with Nasrallah, and with the powerful Iranian Gen. Ghasem Soleimani, highlighting his standing within the group.

Nasrallah in an interview last week also reiterated that Hezabollah reserves the right to retaliate for the assassination of Imad Mughniyeh, which Hezbollah says was carried out by Israel's Mossad.

Also among those killed in Sunday's attack was Mohammad Issa, the only one of the six identified by the Hezbollah statement as a commander. He joined Hezbollah at the age of 15 and was among senior cadres who headed the group's operations in Syria.

Another is Abbas Hijazi, whose father Kamal was one of Hezbollah's founders. Hijazi took part in most of Hezbollah's battles against Israel as well as inside Syria over the past decade.