Israel's military said on Sunday that forces had killed about 20 Palestinian militants in a raid on a northern Gaza hospital, calling it one of its "largest operations" conducted in the territory.

The assault on Kamal Adwan Hospital in northern Gaza's Beit Lahia area began early on Friday, and the World Health Organization said it left the area's last major health facility emptied of patients and staff.

"During the operation, approximately 20 terrorists were eliminated, and powerful explosive devices planted by the terrorists were neutralized," the military said in a statement released on Sunday.

The raid concluded on Saturday after the military said it had apprehended "240 terrorists" belonging to the Hamas and Islamic Jihad militant groups. The military also said it had detained the hospital's director, Hossam Abu Safiyeh, whom it suspects is a Hamas militant.

"This is one of the largest operations to apprehend terrorists conducted in a single location since the beginning of the war," the military said on Sunday.

The WHO has joined growing calls demanding the immediate release of Safiyeh, whose whereabouts remain unknown, warning that hospitals have again become "battlegrounds".

In a post on X, WHO chief Tedros Adhanom Ghebreyesus urged Israel to ensure that patients' and medical workers' healthcare needs and rights are upheld even as attacks continue.

He said Al-Ahli Hospital and Al-Wafa Rehabilitation Hospital in Gaza City also faced attacks and "both are damaged".

Arab League Secretary-General Ahmed Aboul-Gheit also condemned Israel over the burning of Kamal Adwan Hospital.

In a statement published by the Kuwait News Agency or KUNA, Aboul-Gheit said that Israel's "war crimes" in Gaza would not be forgotten and that the international silence toward these crimes was a "stain on the world conscience".

He stressed that targeting the hospital and its personnel and besieging it for weeks was "an unprecedented insistence on dehumanization of Gazans".

In an update on Saturday, the Euro-med Human Rights Monitor published some harrowing testimonies of serious crimes committed by the Israeli army against civilians during the storming of Kamal Adwan Hospital and the surrounding areas.

Overnight, hundreds of tents were flooded in displacement camps in different areas of the Gaza Strip due to heavy rains, Wafa news agency reported. It said the displaced, particularly in Deir al-Balah, and Al-Mawasi in Khan Younis in the southern Gaza Strip, spent a harsh night inside their cold and flooded tents.

A sixth infant died of cold in the Gaza Strip on Monday in less than a week as winter set in amid the lack of heating facilities, Wafa news agency reported. A few days ago, four victims between the ages of 4 and 21 days died due to severe cold.

Agencies contributed to this story.