Israel ally the United States said it would move warships and fighter jets to the region, while Western governments called on their citizens to leave Lebanon -- where the powerful Iran-backed Hezbollah movement is based -- and airlines cancelled flights.

The killing this week of Hamas leader Ismail Haniyeh in Tehran, hours after the Israeli assassination of Hezbollah's military chief in Beirut, has triggered vows of vengeance from Iran and the so-called "axis of resistance".

Iran-backed groups from Lebanon, Yemen, Iraq and Syria have already been drawn into the nearly 10-month war between Israel and Palestinian militant group Hamas in Gaza.

Israel on Saturday again traded fire with Hezbollah, carried out a deadly raid in the occupied West Bank, and struck a school compound in Gaza City in an attack that the Hamas-ruled territory's civil defence agency said killed at least 17 people.

Numerous schools turned into displacement shelters have been hit across Gaza in recent weeks, with Israel insisting the facilities had been used by militants. Hamas denied using civilian infrastructure for military activities.

Haniyeh was buried on Friday in Qatar, where he had been based. Israel, accused by Hamas, Iran and others of carrying out the attack, has not directly commented on it.

Iran said on Saturday it expects Hezbollah to hit deeper inside Israel and no longer be confined to military targets.

The Pentagon said it was bolstering its military presence in the Middle East to protect US personnel and defend Israel.

It said an aircraft carrier strike group led by the USS Abraham Lincoln would be deployed, as well as additional ballistic missile defence-capable cruisers and destroyers and a new fighter squadron.

US President Joe Biden, at his beach home in Delaware, was asked by reporters if he thought Iran would stand down.

"I hope so," he said. "I don't know."

Soon after, Hezbollah announced it had fired dozens of Katyusha rockets at the northern Israeli settlement of Beit Hillel.

Israel's army said early Sunday about 30 projectiles had been launched from southern Lebanon into Israel, with most of them shot down and no injuries reported.

Take 'any ticket available' 

In Beirut, 20-year-old student Diana Abu Aasel told AFP she feared "something bad will happen to my family and friends.

"If there is war, I don't think I will be able to bear staying" in Lebanon, she said.

Crowds of thousands rallied Saturday in Morocco, Jordan and Turkey to denounce Haniyeh's killing and show solidarity with Palestinians, AFP correspondents reported.

Haniyeh's killing is among a series of attacks since April that have heightened fears of a regional conflagration.

His death came hours after Israel struck south Beirut, killing Hezbollah military commander Fuad Shukr.

Both Britain and the United States on Saturday urged their citizens in Lebanon to leave immediately.

Canada told its nationals to avoid all travel to Israel due to the "unpredictable security situation".

Israel has vowed to destroy Hamas in retaliation for its unprecedented October 7 attack which triggered war in Gaza and resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on Israeli official figures.

Militants also seized 251 hostages, 111 of whom are still held captive in Gaza, including 39 the military says are dead.

Israel's campaign against Hamas has killed at least 39,550 people in Gaza, according to the territory's health ministry, which does not give details of civilian and militant deaths.

Haniyeh was Hamas's lead negotiator in efforts to end the war. His killing raised questions about the continued viability of efforts by Qatari, Egyptian and US mediators to broker a truce and exchange of hostages and prisoners.

Hamas officials but also some analysts and protesters in Israel have accused Prime Minister Benjamin Netanyahu of prolonging the war to safeguard his ruling hard-right coalition.

Protesters in several Israeli cities Saturday renewed their calls for a hostage-release deal.

Disease spreading in Gaza 

US Secretary of State Antony Blinken spoke separately with his French and British counterparts on Saturday about the situation in the Middle East, State Department spokesman Matthew Miller said.

Blinken, UK Foreign Secretary David Lammy and French Foreign Minister Stephane Sejourne all agreed on the need for restraint on all sides in the region, Miller said in a statement.

Violence has also surged in the Israeli-occupied West Bank. Palestinian official sources said two Israeli air strikes killed nine people in the north of the territory Saturday.

The military said it had "eliminated terrorist cells".

The war in Gaza has caused widespread destruction and displaced almost the entire population of the territory where, the UN said on Friday, public health conditions "continue to deteriorate".

It said nearly 40,000 cases of Hepatitis A, spread by contaminated food and water, have been reported since the war began.

Hezbollah has been exchanging near-daily cross-border fire with Israeli forces since October, saying it is acting in support of Hamas.

Several airlines have suspended flights to Beirut and Tel Aviv.

Flights to Beirut by Air France and low-cost carrier Transavia France will remain halted until at least Tuesday, their parent company said Saturday.

Turkish Airlines on Saturday cancelled its night-time flights to Tehran for the second night running, AFP correspondents noted.