The head of the World Health Organization has called for an end to attacks on hospitals in Gaza.

"Hospitals in Gaza have once again become battlegrounds and the health system is under severe threat," Dr Tedros Adhanom Ghebreyesus said.

His warning came after the last functioning hospital in besieged northern Gaza, Kamal Adwan, was raided and forcibly evacuated by the Israeli military on Friday and two hospitals in Gaza City were attacked on Sunday. The military said two of the sites were being used as Hamas command centres.

Dr Tedros also joined rights groups and relatives calling for the immediate release of Kamal Adwan's director, Dr Hussam Abu Safiya, who was detained by Israeli forces.

The Israeli military said on Saturday that his hospital was a Hamas "stronghold" and that troops had killed about 20 "terrorists" and detained 240 others during the raid. It added that Dr Abu Safiya was among those taken for questioning and that he was "suspected of being a Hamas terrorist operative".

The military did not provide evidence for the allegations, which Hamas dismissed as "lies".

US-based MedGlobal condemned the detention of Dr Abu Safiya, who was its lead physician in Gaza, as "not only unjust" but also "a violation of international humanitarian law, which upholds the protection of medical personnel in conflict zones".

Dr Abu Safiya's family expressed concern about his health, saying he was still recovering from severe injuries sustained in an attack last month and that he was likely to be suffering from the cold because he had been forced to strip off his clothes.

Hamas also dismissed the Israeli allegations as "lies".

Dr Tedros said Kamal Adwan was out of service following the raid and that its critically ill patients had been transferred to the "out of function" Indonesian hospital, which he warned was severely damaged and had no ability to provide care.

"Amid ongoing chaos in northern Gaza, WHO and partners today delivered basic medical and hygiene supplies, food and water to Indonesian hospital and transferred 10 critical patients to al-Shifa Hospital [in Gaza City]," he said.

"Four patients were detained during the transfer. We urge Israel to ensure their health care needs and rights are upheld."

Gaza's Hamas-run health ministry said one of those detained patients was in a critical condition, and that seven patients and 10 medical staff remained at the Indonesian hospital.

Israeli forces launched a major ground offensive in the northern towns of Jabalia, Beit Lahia and Beit Hanoun on 6 October, saying it was stopping Hamas from regrouping there. The UN says the areas are under near-total siege and that humanitarian assistance has been largely denied by Israeli forces for more than 11 weeks.

Dr Tedros also said al-Ahli hospital and al-Wafa Rehabilitation hospital in Gaza City "also faced attacks" and were both damaged.

On Sunday, seven people were killed and other seriously wounded in an Israeli strike on the upper floor of al-Wafa hospital, according to the Hamas-run Civil Defence agency.

The Israeli military said the strike targeted Hamas fighters who were using the building as a command and control centre. It added that the building was not serving as a hospital at the time.

But a witness told the BBC there were patients and medical staff inside the hospital.

A fourth-year medical student said she had been inside the hospital with her colleagues, getting ready to sit an exam, when it was bombed.

"There was heavy smoke and we nearly suffocated. Glass from destroyed windows fell over us. We took cover under the tables and then fled," she added.

"As we were coming down the stairs, we saw patients on wheelchairs, others being carried. Our professor suffered a head injury and was bleeding - some other colleagues had minor injuries."

The wounded were taken to the al-Ahli hospital, which was apparently hit by Israeli shelling earlier on Sunday.

Video footage posted online appeared to show damage to the top floor of one building at the site.

The Israeli military has not commented on the reports.

A displaced man living in the vicinity of the al-Ahli hospital told BBC Arabic that he was afraid that it would be the next to be raided by Israeli forces.

"If they besiege us here, where can we go then? How long will this suffering continue? We have been displaced about six or seven times," he said. "They have bombed all homes, schools and hospitals. There is no longer a safe place for us to take shelter in."

Israel launched a campaign to destroy Hamas in response to the group's unprecedented attack on southern Israel on 7 October 2023, in which about 1,200 people were killed and 251 others were taken hostage.

More than 45,540 people have been killed in Gaza since then, according to the territory's health ministry.