It also urged residents to donate blood at Nasser hospital in western Khan Younis to help treat the large number of casualties being brought to the facility.
Much of Gaza’s second city was destroyed in an Israeli offensive earlier this year, but large numbers of people returned there after Israeli troops began an operation in the southernmost city of Rafah in May.
At the start of this month, tens of thousands were displaced once again after the Israeli military issued a fresh evacuation order for other eastern neighbourhoods of Khan Younis as well as nearby towns and villages.
They were instructed to go to the humanitarian zone – which stretches along the coast from al-Mawasi to the central town of Deir al-Balah – despite warnings from the UN that it was already overcrowded with tents and lacking basic services.
Israel has also carried out several deadly strikes in the humanitarian zone in the past two weeks, which it has said targeted Palestinian fighters operating there.
On 13 July, the Gaza health ministry said more than 90 people had been killed in an Israeli strike inside al-Mawasi that targeted the head of Hamas’s military wing.
The Israeli military said on Friday that there were “increasing signs” that Mohammed Deif was among the dead, but that Hamas was hiding what had happened to him. The military also confirmed again that the commander of Hamas’s Khan Younis brigade was killed in the strike.
In a separate development on Monday, the head of the UN agency for Palestinian refugees (Unrwa) accused Israeli forces of firing at a marked UN convoy that was heading to Gaza City.
One armoured car was hit by at least five bullets while waiting near an Israeli checkpoint south of the Wadi Gaza river valley on Sunday, Philippe Lazzarini wrote on X, formerly Twitter.
The vehicle was severely damaged and UN personnel were forced to take cover, but there were no casualties, he added.
Mr Lazzarini said the convoy’s movement had been co-ordinated with Israeli authorities and demanded that “those responsible must be held accountable”.
The Israeli military said it was checking the report.
Israel launched a campaign in Gaza to destroy Hamas in response to an unprecedented attack on southern Israel on 7 October, during which about 1,200 people were killed and 251 others were taken hostage.
More than 38,980 people have been killed in Gaza since then, according to the territory’s health ministry.