The United Nations called Tuesday for international investigators to be granted to access to all of Gaza "to assist with evidence-gathering" as hundreds of bodies are pulled from the rubble.

"The discovery of extensive remains under the rubble in Gaza City resurfaces these concerns of war crimes and other atrocity crimes," U.N. rights chief Volker Turk said in a statement.

Prime Minister Benjamin Netanyahu warned on Monday of heavy reprisals on Israel's enemies if they attacked, as he lauded the recent demolition of a Hezbollah tunnel network in southern Lebanon.

Netanyahu said Israel's destruction of Hezbollah positions at the Beaufort and Ali al-Taher ridges was a "massive victory" and vowed to "continue to destroy terrorist infrastructure".

Yemen's Houthis said Monday they had fired dozens of drones and ballistic missiles at military targets in Saudi Arabia, in retaliation for airstrikes by Riyadh.

"The Yemeni armed forces conducted a large-scale military operation targeting military installations and infrastructure, including fighter jet hangars, radars, runways, ammunition depots, and other targets located at King Khalid Air Base in Khamis Mushait," said Houthi military spokesman Yahya Saree.

Iran's foreign ministry on Monday denied the country had any involvement in the war in Yemen, after the Iran-backed Houthi movement seized more territory.

"Iran does not interfere in Yemeni affairs," ministry spokesman Esmaeil Baqaei told reporters, saying the Houthis are "entirely independent actors who make their decisions based on their own interests".

The EU's top diplomat said Monday that Russian strikes which hit a Warsaw-bound train near Ukraine's border with Poland shortly after top Western figures passed through were meant to "scare" off Kyiv's backers.

"It is clearly meant to scare Western countries from supporting Ukraine, from going to Ukraine to show support," foreign policy chief Kaja Kallas said, urging Kyiv's backers to do "the opposite".

Iran said a planned meeting with Gulf countries in Oman on Monday to discuss the Strait of Hormuz was postponed at the request of Saudi Arabia, which cited the war in Yemen.

"It is true that Saudi Arabia asked for this meeting to be postponed," said foreign ministry spokesman Esmaeil Baqaei. "Invoking the Yemeni issue as the reason is a false pretext," he added at a press conference in Tehran attended by AFP.

Israel's demolition on Thursday of a tunnel network used by Hezbollah as a command center in southern Lebanon, near the border, represents a significant setback for the Iran-backed group.

Experts said that while Hezbollah is far from defeated, the group was now exposed after two fierce wars with Israel in which it suffered major blows including the loss of much of its top leadership and Israel's occupation of parts of southern Lebanon.

Houthi fighters on Sunday said they used drones and missiles to attack a military base in southern Saudi Arabia as renewed fighting with Yemen's government forces forced growing numbers of civilians to flee.

Iraqi authorities announced on Sunday a timeline to reopen three crossings with Iran, a day after closing them following a drone attack originating from their shared border on a Saudi pipeline.

After the Friday night attack on the East-West pipeline, Baghdad sacked the military commander in Missan province near the Iran border, after authorities determined the drones were launched from there.

A ship was struck in the Strait of Hormuz on Sunday, killing one person and injuring three, local Iranian authorities said, as Tehran and Washington clash over the strategic waterway.