Israel said on Sunday it would strike hard against Hezbollah after accusing the Iran-backed group of killing 12 children and teenagers in a rocket attack on a football field in the Israeli-occupied Golan Heights.

Hezbollah denied any responsibility for the attack on Majdal Shams, the deadliest in Israel or Israeli-annexed territory since Hamas' Oct. 7 assault sparked the war in Gaza, which has since spread to several fronts.

Prime Minister Benjamin Netanyahu ended a visit to the United States early and was expected to land in Israel later on Sunday and convene his security cabinet on Sunday afternoon to discuss Israel's response.

In the meantime, families gathered for funerals in the Druze village of Majdal Shams in the Golan Heights, territory captured from Syria by Israel in the 1967 Middle East war and annexed in a move not recognised by most countries.

The football pitch was hit on Saturday evening. Hezbollah had earlier announced it had fired rockets at Israeli military sites, but swiftly denied involvement in the attack on Majdal Shams, saying it had "absolutely nothing to do with the incident, and categorically denies all false allegations in this regard."

"Contrary to its denials, Hezbollah is the entity that is unequivocally responsible for yesterday's massacre," Israel's foreign ministry said. "The rocket that murdered our boys and girls was an Iranian rocket and Hezbollah is the only terror organization which has those in its arsenal."

An Israeli military spokesperson had earlier told reporters that forensics showed the rocket was an Iranian-made Falaq-1. Hezbollah had announced firing a Falaq-1 missile on Saturday, saying it had aimed at an Israeli military headquarters.

Defence Minister Yoav Gallant visited Majdal Shams and said: "We will hit the enemy hard."

The Israeli military said the rocket launch was carried out from an area located north of the village of Chebaa in southern Lebanon.

Several aerial attacks hit towns in southern Lebanon and one location in the vast eastern Bekaa Valley overnight and into Sunday morning, according to security sources in Lebanon.

Israel's military said it struck a series of Hezbollah targets deep inside Lebanon overnight but any large-scale operations would likely require security cabinet approval.