At least 29 Palestinians have been killed in an Israeli air strike on a residential building in the east of Gaza City, a local hospital says.

The Hamas-run Civil Defence agency said warplanes targeted the area near al-Hawashi mosque in the Shejaiya neighbourhood on Tuesday morning.

It said more than 40 people were wounded and that rescuers were still searching for bodies in the rubble.

The Israeli military said it had struck a "senior Hamas terrorist" who was responsible for planning and executing attacks in the area.

Numerous steps were taken to mitigate harm to civilians, including the use of "precision weapons", it added.

The military also accused Hamas of violating international law by deliberately using the civilian population as human shields.

Ayub Salim, 26, told AFP news agency that the area around the residential building struck on Tuesday morning had been "overcrowded with tents, displaced people and homes".

He said it was hit by "multiple missiles" and that "shrapnel flew in all directions".

"Dust and massive destruction filled the entire place, we couldn't see anything, just the screams and panic of the people," he said. "It is truly a horrific massacre."

Thousands of Shejaiya residents fled last week after the Israeli military ordered the evacuation of the neighbourhood, saying it was operating with force to destroy "terrorist infrastructure" .

Earlier on Tuesday, Gaza's Hamas-run health ministry said at least 33 people had been killed in Israeli attacks over the previous 24 hours.

That brought the reported total of those killed since Israel resumed its air and ground campaign against Hamas on 18 March to 1,482.

Another 390,000 people have been displaced over the past three weeks, with two-thirds of the territory now designated by the Israeli military as "no-go" zones or placed under evacuation orders, according to the UN.

The UN has also warned that supplies of food, medicine and fuel have dried up because Israel has prevented any deliveries of humanitarian aid for a month to put pressure on Hamas.

On Tuesday, Secretary General António Guterres condemned the Israeli blockade, saying it violated international law and had opened "the floodgates of horror".

"Gaza is a killing field and civilians are in an endless death loop," he added.

The Israeli foreign ministry rejected Guterres' criticism, saying he had "not let the facts get in the way when spreading slander against Israel".

"There is no shortage of humanitarian aid in the Gaza Strip - over 25,000 aid trucks have entered the Gaza Strip in the 42 days of the ceasefire. Hamas used this aid to rebuild its war machine," spokesman Oren Marmonstein said.

The heads of six UN humanitarian agencies had earlier described Israel's assertion that there was enough food as "far from reality on the ground".

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 50,840 people have been killed in Gaza since then, according to the territory's health ministry.