Fierce air and artillery strikes rang out in Gaza early on Monday as Israeli troops backed by tanks pressed into the Palestinian enclave with a ground assault that prompted more international calls for civilians to be protected.

Israel's military said it had struck more than 600 militant targets over the past few days as it expanded ground operations in the Gaza Strip, where Palestinian civilians are in dire need of fuel, food and clean water as the war enters its fourth week.

"IDF troops killed dozens of terrorists who barricaded themselves in buildings and tunnels, and attempted to attack the troops," a military statement said.

Israel began a major push into Gaza on Friday and reiterated calls for civilians to move from the north of the tiny coastal enclave to the south as it tries to root out Hamas militants it says are hiding in a labyrinth of tunnels under Gaza City.

In what appeared to be an effort to cut off the city, Israeli forces carried out dozens of air strikes on its eastern side, residents said, with some reporting the roar of tanks rolling in amid heavy exchanges of fire.

To the west, where Israel on Sunday showed tanks on the Mediterranean coast, the north-south coast road was hit several times, residents said. Internet and phone connections remained largely cut off in the north, making communication difficult.

Many Palestinians have remained in Gaza City, afraid to lose their homes and concerned by news of Israeli air strikes further south.

Medical officials in Al-Shifa and Al-Quds hospitals said air strikes had hit near their buildings. The U.N. humanitarian office OCHR said 117,000 civilians are sheltering alongside thousands of patients and doctors in hospitals in the north.

Israel has accused Hamas of locating command centres and other military infrastructure in Gaza hospitals, which the group denies.

Air strikes could also be heard in the southern towns of Rafah near Gaza's border crossing with Egypt, the only one not blocked by Israel, as well as east of Khan Younis, where Palestinian media said Hamas clashed with Israeli troops.

Phone and internet cuts which blacked out Gaza on Friday had eased and OCHR said on Monday services were "largely restored" although telecoms providers have said some areas on the north were still down.

Israel has said 1,400 people were killed when Hamas-led militants stormed through the south of the country on Oct. 7 and took 229 hostages. Hamas has released four so far and said 50 have been killed in retaliatory strikes.

Medical authorities in Hamas-run Gaza, which has a population of 2.3 million people, said on Sunday 8,005 people - including 3,324 minors - had been killed.

OCHR said rescuers were struggling to reach people.

"As of 29 October, about 1,800 people, including at least 940 children, have been reported missing and may be trapped or dead under the rubble, awaiting rescue or recovery," it said.

It also said that armed groups continued firing rockets at Israel indiscriminately, with no fatalities reported.

The Israeli defence ministry issued video footage of what it said were maneuvers inside Gaza showing soldiers stationed inside buildings, tanks on a main road, and air strikes on what it said were buildings occupied by Hamas.

Reuters was not able to independently verify the exact timing or location of the video and Israel's military said it would not reveal where it was filmed.

"We are moving from the ground, spotting the terrorists and attacking from the air. There is also direct engagement between ground forces and terrorists. The fighting is taking place inside the Gaza Strip," military spokesperson Daniel Hagari said.

Islamist groups Hamas and Islamic Jihad said their members were also fighting Israeli forces in the Israeli-occupied West Bank city of Jenin, where scores of Palestinians have been killed and hundreds arrested since Oct. 7.

Israel said on Monday it had arrested 700 Hamas militants in the West Bank, where it says its forces often come under fire while trying to detain them.

The Palestinian health ministry said four people were killed during a raid in Jenin early on Monday. Israel said several fighters were killed in an air strike there.

The conflict has spurred large demonstrations worldwide in support of the Palestinians, and antisemitic and Islamophobic harassment and attacks are increasing.

Russian authorities said they had taken over an airport in the predominantly Muslim Dagestan region and arrested 60 people after hundreds of anti-Israel protesters stormed the facility on Sunday when a plane from Israel arrived.

Twenty people were wounded at the airport before security forces contained the unrest, local authorities said. The passengers on the plane were safe, security forces told Reuters.

Israel's widening ground attacks on Gaza have spurred international calls for a "humanitarian pause" to allow aid in.

Qatar-mediated negotiations between Israel and Hamas continued on Sunday, a source briefed on the talks told Reuters, and included discussions about the possible release of hostages.

Hamas wants a five-day pause in Israel's operations to allow aid and fuel into Gaza in return for the release of all civilian hostages held by the militants, said the source, speaking on condition of anonymity.

More than half the hostages held by Hamas have foreign passports from 25 countries, the Israeli government says.

OCHA said 33 trucks carrying water, food and medical supplies had entered Gaza on Sunday, the biggest delivery so far, but that much bigger daily deliveries were required to meet urgent needs and prevent civil unrest. People stormed aid stores on Sunday in search of food.

U.S. President Joe Biden has warned Iran, which backs Hamas and other militant groups in the region, not to stir up the conflict. Iran said on Monday that Washington should stop blaming it for the violence.

There are fears that the war will spill over into the region, including in Lebanon, where the Israeli army and Iranian-backed Hezbollah group have been exchanging fire.

On Monday, Syrian state TV said Israeli air strikes targeted two army posts in Daraa, leading to "some material losses".

(Reuters)

Smoke rises over Gaza, as seen from Israel's border with Gaza, in southern Israel. (Reuters)

Fierce clashes in Gaza as Israeli forces expand ground offensive