Friday's strikes fuelled concerns of a wider regional conflagration.

They targeted "a rocket depot belonging to Lebanon's Hezbollah" near the Aleppo airport in northern Syria, according to the Britain-based Syrian Observatory for Human Rights.

It was the latest deadly raid on Iran-backed forces in Syria, where Hezbollah has been backing the government in its fight against opponents since the 2011 Syria civil war erupted.

Israeli strikes on targets in Syria have increased since Israel's war against the Hezbollah-allied Hamas group in the Gaza Strip broke out on October 7.

Israeli raids also regularly target Hezbollah in Lebanon in retaliation for cross-border fire.

Friday's strikes killed 38 Syrian soldiers, seven Hezbollah members and seven Syrian pro-Iran fighters, the Observatory said, up from a total of 44 according to an earlier toll.

The number of Syrian soldiers killed was the highest in Israeli strikes since the war with Hamas broke out, said the war monitor, which relies on a network of sources in Syria.

Israel rarely comments on individual strikes, and has neither confirmed nor denied the raids on Syria.

But Israel's military has said it killed the deputy head of Hezbollah's rocket unit in Lebanon, Ali Naim, whose death the Iran-backed group confirmed.

Israeli Defence Minister Yoav Gallant said on social media that he visited northern Israel on Friday "to closely examine another successful termination like the one that was executed this morning", in Lebanon and Syria.

Israel's army would keep up its operations against Hezbollah everywhere, he said, adding: "We will make them pay a price for every attack that comes out from Lebanon."

Hezbollah, which has a powerful arsenal of rockets and missiles, has exchanged near-daily fire with the Israeli military since Hamas's unprecedented October attack on southern Israel triggered the war in Gaza.

"Syria and Lebanon have become one extended battleground from the Israeli perspective," Riad Kahwaji, head of the Institute for Near East and Gulf Military Analysis, told AFP.