Israeli forces stepped up airstrikes across the Gaza Strip on Thursday, killing at least 40 people, Palestinian medics said, in further battle with Hamas-led militants as Israel braced for potential wider war in the region.

Israeli airstrikes hit a cluster of houses in central Gaza's Al-Bureij camp, killing at least 15 people, and the nearby Al-Nuseirat camp, killed four, medics said. Nuseirat and Bureij are among the densely populated enclave's eight historic camps and seen by Israel as strongholds of armed militants.

Israeli aircraft also bombed a house in the heart of Gaza City in the north, killing five Palestinians, while another airstrike in the southern city of Khan Younis killed one person and wounded others, according to medics.

Later on Thursday, 15 Palestinians were killed and 30 injured in Israeli bombings of two schools east of Gaza City, the territory's Civil Emergency Service said in a statement.

The Israeli military said it struck Hamas command and control centres embedded in the Abdel-Fattah Hamouda and Al-Zahra schools in the Tuffah neighbourhood of Gaza City, where Hamas militants were operating.

It accused Hamas of exploiting civilians and civilian properties for military purposes, an allegation Hamas denies.

Footage circulated on social media, which Reuters could not immediately verify, showed casualties being brought to a hospital on donkey carts.

The armed wings of Hamas and Islamic Jihad said they were firing anti-tank rockets and mortar bombs at Israeli forces operating across Gaza, causing deaths and injuries among them.

Israel's military said it had struck dozens of military targets across Gaza over the past 24 hours, including rocket launching pads.

Hamas-led militants set off the Gaza war on Oct. 7 last year with a shock, cross-border rampage into Israeli communities, killing 1,200 Israelis and foreigners and seizing some 250 hostages, according to Israeli tallies.

Since then, at least 39,699 Palestinians have been killed, including 22 within the past 24 hours, and 91,722 injured in Israel's devastating air and ground war in Gaza, the Gaza health ministry said in an update on Thursday.

The ministry in the Hamas-run territory does not distinguish between combatants and civilians in its death lists.

As Gaza's war churns on, Israel has been battening down for another attack expected in the coming days following vows from Iran and its Lebanon proxy Hezbollah to retaliate for the assassinations last week of Hamas leader Ismail Haniyeh in Tehran and Hezbollah military commander Fouad Shukur in Beirut.

A relatively contained conflict between Israel and Hezbollah along its northern border, a spillover from the Gaza fighting, now threatens to spiral into an all-out regional war.