Israel has bombarded central and southern Gaza, killing at least 28 Palestinians as tanks have advanced to the south-western edges of Rafah.

It comes one month after tanks entered Rafah in what Israel said was an assault to wipe out Hamas' last intact combat units.

Residents said tanks were stationed in the al-Izba district near the Mediterranean coast while snipers had commandeered some buildings and high ground, trapping people in their homes.

They said Israel machine gun fire had made it too dangerous to go out.

Gaza health officials said two Palestinians had been killed and several wounded in western Rafah from tanks shelling there.

In central Gaza, Palestinians medics said at least 15 people died overnight in Israeli bombardments.

"I think the occupation forces are trying to reach the beach area of Rafah," one Palestinian resident said.

In the larger city of Khan Younis just to the north of Rafah, an Israeli airstrike on a house killed eight people and wounded several, including children, medics said.

In north Gaza, three Palestinians were killed in an Israeli airstrike on a Gaza City school building that was sheltering displaced families, rescue workers said.

Hamas said on Friday militants in the central city of Deir al-Balah shelled a house where Israeli troops were barricaded, killing some and wounding others.

It said helicopters were seen landing to extricate the stricken Israeli unit.

The Israeli military focused on central Gaza in its latest update, saying it had killed "dozens" of militants and destroyed more militant infrastructure in continuing operations in the al-Bureij refugee camp and nearby city of Deir al-Balah.

US backed Qatari and Egyptian mediators have tried again this week to reconcile clashing demands preventing a halt to the hostilities, a release of Israeli hostages and Palestinians jailed in Israel, and an untrammelled flow of aid into Gaza to alleviate a humanitarian disaster.

Israel's military blames Hamas for Gaza's high civilian death toll, accusing it of operating within densely populated neighbourhoods, schools and hospitals as cover, something it denies. UN and humanitarian officials accuse Israel of using disproportionate force in the war, which it denies.

On Thursday, Israel hit an al-Nuseirat school building with what it said was a targeted air strike on up to 30 militant combatants inside.

A Hamas official said 40 people were killed, including women and children sheltering at the UN site.

"It's just another horrific example of the price that civilians are paying, that Palestinian men, women and children who are just trying to survive, who are being forced to move around in sort of a death circle around Gaza, trying to find safety, are paying," UN spokesperson Stephane Dujarric said.

Israel has ruled out peace until Hamas is eradicated, and much of Gaza lies in ruins, but Hamas has proven resilient, with militants resurfacing to fight in areas where Israeli forces had previously declared to have defeated them and pulled back.

Hamas precipitated the war when militants stormed from Israeli-blockaded Gaza into southern Israel in a lightning strike last October 7, killing around 1,200 people and taking over 250 hostages back to the enclave, according to Israeli tallies.