Deadly Israeli air strikes have been reported in Gaza, as Israel’s defence minister said its military would expand its offensive and seize large areas of the Palestinian territory – incorporating them into what he described as “security zones”.

Israel Katz said the expanded operation aimed to “destroy and clear the area of terrorists and terrorist infrastructure”, and would require a large-scale evacuation of Palestinians.

Later, at least 19 people, including nine children, were killed in a strike on a UN clinic sheltering displaced families in the northern town of Jabalia, a local hospital said.

The Israeli military said it targeted “Hamas terrorists” hiding there.

Overnight strikes across Gaza killed at least another 15 people, according to local hospitals.

The Civil Defence said its first responders recovered the bodies of 12 people, including children and women, from a home in the southern Khan Younis area.

Rida al-Jabbour said a neighbour and her three-month-old baby were among the dead.

“From the moment the strike occurred we have not been able to sit or sleep or anything,” she told Reuters news agency.

The Israeli military said it was looking into the reports.

The Civil Defence said the strike in Jabalia later on Wednesday hit two rooms in a clinic run by the UN agency for Palestinian refugees (Unrwa) which was being used as a shelter.

Video verified by the BBC showed dozens of people and ambulances rushing to the building. Smoke was seen billowing from a wing where two floors appeared to have collapsed.

The Israeli military said in a statement that it targeted Hamas operatives who were “hiding inside a command-and-control centre that was being used for co-ordinating terrorist activity and served as a central meeting point”.

“Prior to the strike, numerous steps were taken to mitigate the risk of harming civilians, including the use of aerial surveillance and additional intelligence,” it added.

There was no immediate comment from Unrwa.

There were also reports of extensive Israeli air strikes and shelling along the Egypt border overnight and there is a growing sense that a new major Israeli ground offensive is looming in Gaza.

Israeli Army Radio said on Wednesday that Israeli tanks and ground forces had begun to advance into central and eastern parts of the southernmost city of Rafah.

This week, Israel’s military ordered an estimated 140,000 people in Rafah to leave their homes and issued new evacuation orders for parts of northern Gaza.

Israel has already significantly expanded a buffer zone around the edge of Gaza over the course of the war, and seized control of a corridor of land cutting through its centre.

Israel launched its renewed Gaza offensive on 18 March, blaming Hamas for rejecting a new US proposal to extend the ceasefire and free the 59 hostages still held captive in Gaza.

Hamas, in turn, accused Israel of violating the original deal they had agreed to in January.

The Hostages and Missing Families Forum in Israel, which represents many hostages’ relatives, said they were “horrified to wake up” to the news of the expanded military operation.

The group urged the Israeli government to prioritise securing the release of all hostages still held in Gaza.

In his statement announcing plans to seize more territory, Katz also urged Gazans to act to remove Hamas and free remaining Israeli hostages, without suggesting how they should do so.

The humanitarian situation across Gaza has dramatically worsened in recent weeks, with Israel refusing to allow aid into the Gaza Strip since 2 March – the longest aid blockage since the war began.

Last month the UN announced it was reducing its operations in Gaza, one day after eight Palestinian medics, six Civil Defence first responders and a UN staff member were killed by Israeli forces in southern Gaza.

The Israeli military launched a campaign to destroy Hamas in response to an unprecedented cross-border attack on 7 October 2023, in which about 1,200 people were killed and 251 were taken hostage.

More than 50,399 people have been killed in Gaza during the ensuing war, according to the Hamas-run health ministry.