The struggle to survive continues in northern Gaza as Israel’s devastating siege and bombing of the area enters its 23rd day.

An Oxfam official told Al Jazeera on Sunday Israel is using starvation as a weapon in its genocide against the Palestinians and that the United Kingdom-based NGO was unable to reach people in the north because of Israel’s ongoing bombing campaign.

Mahmoud Alsaqqa, who is Oxfam’s food security and livelihood lead in Gaza, warned that some Palestinians are “starving to death” from hunger in northern Gaza and more people will die in the coming days.

“There is nothing. You are talking about tens of days that they are not receiving any supplies,” he said, adding that most Palestinians in the area rely on aid supplies.

Aid agencies say about 96 percent of Gaza’s population is facing high levels of food shortages. According to UNICEF, nine out of 10 children lack the nutrition they need for growth and development. At least 37 children have died of malnutrition or dehydration in a year of war.

The United Nations says Israel has blocked the entry of 83 percent of food aid into the Strip since the war began. It said about 50,000 children below the age of five need urgent treatment for malnutrition by the end of the year.

On Sunday United Nations Secretary-General Antonio Guterres called for an immediate ceasefire, for the release of hostages and “accountability for crimes under international law”.

“The devastation and deprivation resulting from Israel’s military operations in North Gaza are making the conditions of life untenable for the Palestinian population there,” he said on X.

“This conflict continues to be waged with little regard for the requirements of international humanitarian law.”

The Oxfam warning came as Israeli forces bombed more neighbourhoods in northern Gaza on Sunday and humanitarian officials sounded alarm about the ongoing ground assault by Israeli forces which is forcibly displacing tens of thousands of residents out of the area.

At least 35 people were killed in Beit Lahiya on Saturday after the Israeli army targeted five buildings in the north of the Strip. Another 10 people were killed in a separate attack in Beit Lahiya.

Israel’s strikes on the towns of Jabalia, Beit Hanoon and Beit Lahiya in northern Gaza have so far killed about 800 Palestinians during the ongoing siege, the Ministry of Health in Gaza said.

Al Jazeera’s Hani Mahmoud, reporting from Deir el-Balah in central Gaza, said at least 35 people are missing and are feared to be under the rubble, or have been “vapourised” by the force of the Israeli bombs.

Additionally, an Israeli air strike on a house in Jabalia killed several people and wounded others on Sunday morning, Palestinian medics said.

“People were told to evacuate the Jabalia refugee camp in order to avoid being bombed, but by the time they got to areas far from Jabalia in the central and western parts of northern Gaza, they were bombed and maimed in the areas they were told to evacuate to,” said Mahmoud.

“The Israeli soldiers are forcing people to get out of evacuation centres and setting them on fire,” he added.

‘Dying in a genocide’

Francesca Albanese, the UN special rapporteur on the occupied Palestinian territories, said on social media platform X that “the entire population of Gaza is at risk of dying in a genocide that has been announced and executed under our watch”.

Albanese was responding to a statement made by UN humanitarian chief Joyce Msuya on Saturday, warning that “the entire population of north Gaza is at risk of dying” under Israel’s siege.

The International Committee of the Red Cross on Saturday said the ongoing Israeli evacuation orders and restrictions on the entry of essential supplies to the north had left the civilian population in “horrific circumstances”.

“Many civilians are currently unable to move, trapped by fighting, destruction or physical constraint and now lack access to even basic medical care,” it said.

Palestinian health officials said the siege had crippled the healthcare system in northern Gaza and was blocking medical teams from reaching bombed sites.

Israel maintains that its forces have returned to northern Gaza more than a year into the war to root out Hamas fighters who had regrouped there. The Israeli military claimed it “eliminated over 40 terrorists” in the Jabalia area in the past 24 hours, as well as dismantled infrastructure and located “large quantities of military equipment”.

But Mansour Shouman, a Palestinian journalist who used to live in Gaza, said Israel wants to force Palestinians to leave the northern part of the Strip to create settlements there.

“That area has been going through three weeks of very heavy land invasion attempts by the Israelis. You all are hearing what’s happening with the medical services there. You all are hearing what has happened with the implementation of the General’s Plan, which is trying to eradicate the presence of Palestinians in the north of the Gaza Strip … and push them further south, in order to create a buffer zone for the Israelis and then to create settlements there,” Shouman told Al Jazeera.