The World Health Organization says it is “appalled” by an Israeli raid which it said had shut down and partly destroyed the last major hospital still functioning in northern Gaza.

Israel’s “systematic dismantling of the health system” combined with a siege of the population in the north of the coastal strip over the past 80 days “puts the lives of the 75,000 Palestinians remaining in the area at risk”, the WHO said.

It cited initial reports that some departments of the Kamal Adwan hospital in Beit Lahia “were burnt and severely damaged during the raid, including the laboratory, surgical unit, engineering and maintenance department, operations theatre, and the medical store”.

Local sources in Beit Lahia said that most of the medics and nurses detained in Friday’s raid had been released but the hospital’s director, Hussam Abu Safiya, was still unaccounted for.

The Israel Defense Forces did not respond to questions about the raid, but the army was quoted by the BBC as claiming Hamas was using the hospital as a “terrorist stronghold”, and that patients were moved for their own safety.

The WHO statement said that some of the staff and those patients who were in a stable condition were moved to an unnamed nearby location, while others had been forcibly transferred to the Indonesian hospital, so called because its construction was funded by Indonesia, which had been badly damaged by earlier bombing and was no longer functional.

The United Nations organisation said it would send an emergency mission to the Indonesian hospital on Sunday “to safely move patients to southern Gaza for continued care”.

“Kamal Adwan is now empty,” the statement said. “On Friday evening, the remaining 15 critical patients, 50 caregivers and 20 health workers were transferred to Indonesian hospital, which lacks the necessary equipment and supplies to provide adequate care. The movement and treatment of these critical patients under such conditions pose grave risks to their survival.

“The WHO is deeply concerned for their wellbeing, as well as for the Kamal Adwan hospital director, who has been reportedly detained during the raid. The WHO lost contact with him since the raid began.”

Beit Lahia residents said the Indonesian hospital had no water or electricity supply.

“Additionally, some people were reportedly stripped and forced to walk toward southern Gaza,” the WHO said. Some of the medics who had been detained told reporters they had been beaten and stripped by their Israeli captors. Gaza’s health ministry said: “We appeal to the relevant institutions to find a solution for the patients and injured currently in the Indonesian hospital.”

It added that some patients and health workers had died at the Kamal Adwan hospital in fires started by the IDF, and that Abu Safiyeh was “violently beaten by the occupation forces before his arrest”.

A Hamas official, Osama Hamdan, denied there were any of the group’s fighters at the Kamal Adwan hospital, and claimed the targeting of the health facility was part of Israel’s “generals’ plan”. He was referring to a proposal put forward earlier in 2024 by a group of former senior IDF officers to clear northern Gaza of its civilian Palestinian population, to make the area a free-fire zone to take on pockets of Hamas resistance. Although Benjamin Netanyahu’s government officially rejected the plan, some Israeli and Palestinian military analysts believe it is being implemented on the ground, possibly with the ultimate aim (pursued by the far right of the coalition) to colonise the area with Israeli settlements.

On Saturday, the IDF distributed messages to residents of another area of northern Gaza, ordering them to leave.

“The IDF is operating in this area forcefully,” the orders said. “You must evacuate the area immediately and move south along the Salah al-Din road. Moving via another road exposes you to danger.”

In an interview with the Jerusalem Post published on Saturday, Israel’s foreign minister, Gideon Sa’ar, denied that the government intended to build settlements in Gaza, insisting “the goals set by the cabinet do not include such plans”. However, Sa’ar said he envisioned a long term Israeli military presence in the territory.

“My working assumption is that in the foreseeable future, only we can ensure our security,” he said, rejecting the possibility of a foreign peacekeeping force. “I doubt there will be an effective entity that can provide security in Gaza, which is why I believe Israel will need to remain the controlling force from the Mediterranean to the Jordan River, west of the river,” Sa’ar said.