The World Health Organization condemned a deadly strike Tuesday on a hospital in the Gaza Strip and demanded the immediate protection of civilians and health care in the Palestinian enclave.

"WHO strongly condemns the attack on Al Ahli Arab Hospital", the UN health agency's director-general Tedros Adhanom Ghebreyesus said on the social media platform X, formerly Twitter.

The health ministry in the Hamas-run Palestinian territory said Israeli air strikes on the hospital compound sheltering displaced people had killed at least 200 people.

"Early reports indicate hundreds of deaths and injuries," said Tedros.

"We call for the immediate protection of civilians and health care, and for the evacuation orders to be reversed."

Israel's army has told people in the north of the Gaza Strip — nearly half of its 2.4-million population — to head south to safety, ahead of an expected ground offensive.

Tens of thousands of families have flocked to Gaza's overwhelmed hospitals seeking refuge from Israeli military strikes because they had been relatively spared from the Israeli bombing raids.

Israel has been bombing targets in Gaza since Hamas militants from the territory attacked southern Israel on October 7, triggering a war which has left thousands of dead on both sides.

Around 3,000 people have since been killed in Israeli air strikes across the Gaza Strip.

More than 1,400 people in Israel have been killed, the majority gunned down by Hamas militants who crossed from Gaza and attacked border communities.

On Sunday, Tedros said he was gravely concerned by Israeli attacks in which innocent Palestinian civilians and children were "paying the price".

The conflict "is an awful reminder of how quickly the health of millions of people can be put at risk", he said.

"War will bring nothing but destruction and horror.

"Asking 1.1 million people to move from north to south Gaza in such a short window will create a humanitarian tragedy.

"The forced evacuation of patients and health workers will further worsen the humanitarian and public health catastrophe."

The WHO is calling for the restoration of electricity and water in the Gaza Strip, and for conditions to allow "the immediate and safe delivery of food, medical supplies, and other humanitarian aid", said Tedros.