Israel's onslaught on healthcare and emergency services, crippling of humanitarian access and attacks on civilians in Gaza are dismantling the very means of survival, UN humanitarians said on Monday.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) issued the warning after the announcement by World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus that following an Israeli raid on Kamal Adwan Hospital of north Gaza and the detention on Friday of its director, Hussam Abu Safiya, the facility had closed.

On X, Tedros said patients in critical condition were taken to the non-functioning Indonesian Hospital. Dr Safiya's location is unknown and Dr Tedros called for his immediate release.

"Amid ongoing chaos in northern Gaza, WHO and partners today (Monday) delivered basic medical and hygiene supplies, food and water to the Indonesian Hospital and transferred 10 critical patients to Al-Shifa Hospital," Tedros posted. "Four patients were detained during the transfer. We urge Israel to ensure their health care needs and rights are upheld."

Tedros said that hospitals have become battlegrounds, and the health system is under severe threat. He reported attacks on Al-Ahli and Al-Wafa Hospitals in Gaza City, both of which were damaged, and called for stoping attacks on hospitals and securing access to health care.

The OCHA said that on Sunday, it joined the delivery with the WHO, the World Food Program (WFP), the Palestine Red Crescent Society and the UN Department for Safety. The team reported that the hospital has no water, electricity or sanitation.

The office said the team's mission to North Gaza was exceptional, because most of the 150 mission attempts since October have been denied by the Israeli authorities. Even the few that were initially agreed to faced heavy impediments.

It said that between Friday and Sunday, three of four attempts to access the area were denied by Israeli authorities. Only the joint team effort was let through, but it faced significant impediments. "It should not require breaking a siege to help survivors in critical need. Aid workers must be granted safe and unhindered access to assist people wherever they are."

The OCHA said humanitarian access remains systematically hindered across the Gaza Strip. Since Friday, more than 60 percent of the 42 UN-coordinated movements were denied, interfered with or impeded on the ground.

The office said another constraint on delivering aid in Gaza is armed looting of humanitarian relief convoys. Two incidents recorded over the past three days in southern Gaza affected dozens of truckloads of supplies and further exposed drivers to serious risks. Fighting and Israeli restrictions on commercial and other imports also persist. These continue to dangerously paralyze the humanitarian operation when families urgently need more food, shelter materials and clothing to survive winter weather.