A deadly strike hit a school turned shelter in southern Gaza on Tuesday as Israeli forces in the war-ravaged territory's main city pushed on with a major offensive that has again displaced Palestinians.

A hospital source in Khan Yunis in southern Gaza said at least 29 people were killed when the school was hit in nearby Abasan.

The Israeli military said its air force had carried out a strike in the area targeting a "terrorist" and would review the incident.

The United Nations protested on Tuesday over the latest mass evacuation orders issued by Israel in Gaza as the army said it had killed dozens of militants in "close-quarters combat" in its latest offensive in Gaza City.

Israel extended its evacuation warning to cover most of Gaza's main city on Monday and intense fighting erupted.

Israel has now issued three evacuation orders for Gaza City and one for the south of the Palestinian territory since June 27 in a new stepping up of its military operations. The UN says tens of thousands of civilians have fled.

Standing by the faded blue wall of an empty sports hall in Sanaa, Yasameen Al-Raimi raises her air pistol and pauses, studying the target 10 metres away.

Squeezing the trigger, the Yemeni Olympic hope fires a metal pellet through the middle of the paper square, rebounding with a clang off the metal plate behind.

Raimi, in black hijab, safety glasses and yellow ear protectors, is training for the Paris Olympics, one of the biggest competitions of her life.

Riding donkey carts, bicycles or on foot, thousands of Palestinians fled Gaza City on Monday, after Israel issued a third evacuation warning for the city where intense fighting took place.

Civilians have now been ordered out of the majority of the Gaza Strip's largest city, where thousands of families had sought shelter from fighting in other parts of the war-stricken territory.

"Where do we go now?" asked Abdullah Khammash, who described how he left his latest refuge at 03:00 am.

Palestinians on Monday fled heavy battles in Gaza City as the Israeli military expanded an evacuation order and mediators intensified efforts to end the nine-month war between Israel and Hamas militants.

But the Islamist movement's political chief warned that developments on the ground could threaten talks, even as mediators Egypt and Qatar were due to host new meetings this week, according to officials.

Shady websites calling for a boycott of Qatar, a New York billboard targeting the Gulf state's rulers, and a Vietnamese outfit floating hundreds of slander-ridden Facebook ads -- all elements of a sprawling influence operation vilifying the country as it mediates between Israel and Hamas.

The murky operation, which began late last year and spans multiple countries, is the largest ever to target the wealthy emirate, disinformation researchers say, as the nine-month war between Israel and the Palestinian militant group rages on.

Thousands of Moroccans demonstrated Sunday in the northern city of Tangier in support of the Palestinian people and against Morocco's ties with Israel, an AFP journalist saw.

"Gaza is not alone," chanted the protesters during the event which saw the grouping of leftist parties and Islamist movements.

The protesters took to the streets of the coastal city after reports last month of an Israeli ship's docking in Tangier port.

Coming from the United States, the ship made a pit stop in Tangier on June 19, according to Israeli media.

The civil defence agency in Hamas-run Gaza said a second Israeli strike in two days on a school sheltering displaced families killed at least four people, as the UN condemned the targeting of its shelters.

Israel's military said it hit "the area of the school" in Gaza City, adding the school complex was used as a militant hideout and housed "a Hamas weapons manufacturing facility.

The civil defence agency in Hamas-ruled Gaza said Ihab al-Ghusain, the group's deputy labour minister, was among those killed in the strike Sunday on the Holy Family School.

Israeli protesters marched through Tel Aviv and Jerusalem chanting "we will not give up" on Sunday, the second consecutive day of stepped-up pressure for a deal to free hostages in Gaza.

As the war entered into its 10th month, the demonstrators called on Prime Minister Benjamin Netanyahu to secure a truce and hostage-release deal or step down.

The nationwide "disruption day" began at 6:29 am (0329 GMT) to correspond with the start of Hamas's October 7 attack that triggered the war.

A Hamas official said Sunday the Palestinian Islamist group was ready to discuss a hostage release deal with Israel even without a "complete" ceasefire in the Gaza Strip.

The apparent easing of Hamas's position comes as long-stalled diplomatic efforts to secure a ceasefire and hostage release have gathered pace with a new proposal and meetings hosted by Qatari and Egyptian mediators.

"Hamas had previously required that Israel agree to a complete and permanent ceasefire," the top official told AFP as the war entered its 10th month.