Gaza's civil defence agency on Sunday said 30 people, including 13 children, were killed in Israeli strikes on two houses in the north of the Palestinian territory.
The first strike early Sunday hit a house in Jabalia, northern Gaza, killing "at least 25" people, including 13 children, and injuring more than 30, civil defence said.
Since October 6, the Israeli military has been engaged in a withering air and ground assault on areas of northern Gaza, including Jabalia, saying they are seeking to stop Hamas militants from regrouping there.
Another strike on the Sabra neighbourhood of Gaza City killed five people, with others still missing in the aftermath, civil defence said.
"A number of civilians are still under the rubble," the agency added.
Contacted by AFP, the Israeli military said it was "looking into the reports" of the strikes.
The war in Gaza erupted with Hamas's October 7, 2023 attack on southern Israel, which resulted in 1,206 deaths, mostly civilians, according to an AFP tally of Israeli official figures.
Israel's retaliatory campaign has killed 43,552 people in Gaza, most of them civilians, according to figures from the Hamas-run territory's health ministry that the United Nations considers reliable.
The United Nations human rights (OHCHR) office on Friday condemned the number of civilians killed in Israel's war in Gaza, with women and children comprising nearly 70 per cent of the thousands of fatalities it had managed to verify.
"Civilians in Gaza have borne the brunt of the attacks, including through the initial 'complete siege' of Gaza by Israeli forces," the OHCHR said.
"Conduct by Israeli forces has caused unprecedented levels of killings, death, injury, starvation, illness and disease."
Israel's mission to the UN in Geneva "categorically" rejected the report, decrying "the inherent obsession of OHCHR with the demonisation of Israel".
The heads of UN agencies in early November described northern Gaza as "under siege" and denied "basic aid and life-saving supplies."
Israel's main military backer the United States had on October 15 warned that it could withhold some of its billions of dollars in military assistance unless it improves aid delivery to the Gaza Strip within 30 days.
With that deadline fast approaching, there has been little sign of improving conditions, with a UN-backed assessment on Saturday warning famine is imminent in northern Gaza.
Aid shipments allowed to enter the Gaza Strip were now lower than at any time since October 2023, according to the Integrated Food Security Phase Classification (IPC) report.
The alert from the Famine Review Committee warned of "an imminent and substantial likelihood of famine occurring, due to the rapidly deteriorating situation in the Gaza Strip".