Israel bombarded Gaza with air strikes early on Monday. Prime Minister Benjamin Netanyahu convened a meeting of his top generals and his war cabinet to assess the escalating conflict. Overnight Israeli aircraft struck southern Lebanon.

Israel's attacks concentrated on the Gaza Strip's centre and north, Palestinian media reported. A strike on a house near the Jabalia refugee camp, in northern Gaza, killed several Palestinians and wounded others, according to media reports.

Palestinian Hamas leader Ismail Haniyeh and Iranian Foreign Minister Hossein Amirabdollahian discussed in a call late on Sunday the means of stopping Israel's "brutal crimes" in Gaza, Hamas said in a statement.

Israel has amassed tanks and troops near the fenced border around Gaza for a planned ground invasion aiming to annihilate Hamas.

Fears that the Israel-Hamas war could mushroom into a wider Middle East conflict rose over the weekend with Washington warning of a significant risk to US interests in the region and announcing a new deployment of advanced air defenses.

The Pentagon has already dispatched a significant amount of naval power to the Middle East, including two aircraft carriers, support ships and about 2,000 Marines, to help deter attacks by Iran-affiliated forces.

"What we're seeing ... is the prospect of a significant escalation of attacks on our troops and our people throughout the region," US Defense Secretary Lloyd Austin told ABC's "This Week" program on Sunday.

China's Middle East special envoy Zhai Jun, who is visiting the region, warned that the risk of a large-scale ground conflict was rising and that spillover conflicts in the region were "worrisome", Chinese state media said on Monday.

Iranian security officials told Reuters Iran's strategy was for Middle East proxies like Hezbollah to pursue limited strikes on Israeli and US targets but to avoid a major escalation that would draw in Tehran, a high-wire act for the Islamic Republic.

In neighbouring Syria, where Hamas' main regional backer Iran has a military presence, Israeli missiles hit Damascus and Aleppo international airports early on Sunday, putting both out of service and killing two workers, Syrian state media said.

Along Israel's northern border with Lebanon, the Iran-backed Hezbollah group has clashed with Israeli forces in support of Hamas in the deadliest escalation of frontier violence since an Israel-Hezbollah war in 2006.

Early on Monday, Israeli aircraft struck two Hezbollah cells in Lebanon that were planning to launch anti-tank missiles and rockets toward Israel, its military said. Israel's military also said it struck other Hezbollah targets, including a compound and an observation post.

Hezbollah said on Monday that one of its fighters was killed, without providing details.

With violence around its heavily guarded borders increasing, Israel on Sunday added 14 communities close to Lebanon and Syria to its evacuation contingency plan in the north of the country.

More aid arrives in Gaza
Palestinian Prime Minister Mohammad Shtayyeh called on the international community to create "a united front" to stop Israel's attacks in Gaza and allow desperately needed aid which has only begun to trickle in.

A second convoy of 14 aid trucks entered the Rafah crossing to the besieged Gaza Strip on Sunday night, and US President Joe Biden and Netanyahu affirmed in a call "there will now be continued flow of this critical assistance into Gaza," the White House said.

The UN humanitarian office said the volume of aid entering so far was just 4% of the daily average before the hostilities and a fraction of what was needed with food, water, medicines and fuel stocks running out.

Biden also ramped up his diplomacy, convening calls on Sunday with Netanyahu and Pope Francis and speaking with the leaders of Canada, France, Britain, Germany, Italy and Britain about getting aid into Gaza and preventing the conflict from spreading.

In a joint statement, the leaders voiced support for Israel's right to defend itself. They also called for adherence to international humanitarian law, including the protection of civilians.

Netanyahu also held a phone call with the leaders of France, Spain and the Netherlands late on Sunday, the Israeli leader's office said.

Dutch Prime Minister Mark Rutte will visit Israel on Monday and French President Emmanuel Macron will visit Tuesday.