A picture shows smoke billowing from buildings during Israeli bombardment over Khan Yunis, Gaza. AFP

Israeli shelling and airstrikes killed at least 19 people in central and south Gaza on Tuesday including two policemen who were helping protect humanitarian aid deliveries in the southern city of Rafah, Palestinian medics said.

Seventeen of the deaths, they said, occurred in separate Israeli airstrikes on the al-Bureij and al-Maghazi refugee camps and the city of Deir-al-Balah in central Gaza, and by late Tuesday tanks were shelling an area just east of the al-Nusseirat camp, residents said.

Some told Reuters via chat app that the renewed Israeli military push was sowing panic, with some families living in al-Maghazi starting to flee under tank fire, with four shells crashing near a clinic in the camp.

In a brief statement issued earlier in the day, the Israeli military said jets were hitting Hamas targets in central Gaza while ground forces were operating "in a focused manner with guidance from intelligence" in the al-Bureij area.

It gave no update on activity in Rafah, into which Israeli forces swept last month in what the military calls a limited operation to root out Hamas' last intact combat units after almost eight months of devastating war in the Gaza Strip.

The small city fringing Gaza's southern border with Egypt had been sheltering about one million Palestinians who fled Israeli assaults in other parts of the enclave, but most have fled again in the face of Israel's tank-led advance.

The Israeli military campaign has killed more than 36,000 people in densely populated Gaza, according to its health authorities, who say thousands more bodies are buried under rubble.

Buildings lie in ruins after they were destroyed during Israel's military offensive in Gaza City. Reuters

Meanwhile, a response from Palestinian Islamist group Hamas on Israel's ceasefire proposal that US President Joe Biden revealed on Friday is still being awaited, White House national security adviser Jake Sullivan told reporters on Tuesday.

"We are waiting for a response from Hamas" through the Qatari mediators, Sullivan said.

CIA Director Bill Burns will be in Doha to consult with Qatari mediators on the Gaza ceasefire proposal, Sullivan added. Qatar has been mediating on Gaza between Israel and Hamas.

Qatar said on Tuesday it had delivered the Israeli ceasefire proposal to Hamas that reflected a three-phase proposal presented by Biden, and that the paper was now much closer to the positions of both sides.

A spokesman for Hamas, which has ruled Gaza since 2007, reiterated on Tuesday it could not agree to any deal unless Israel makes a "clear" commitment to a permanent truce and complete withdrawal from Gaza.

US President Joe Biden speaks during a press conference. File photo

For his part, Israeli Prime Minister Benjamin Netanyahu has also repeated that there can be no permanent peace unless Hamas is eradicated, as he struggles with profound political divisions at home over the US-backed truce proposal.

Israel's assault on Gaza has killed more than 36,000, according to the local health ministry, caused widespread hunger, flattened most of the enclave and led to genocide allegations that Israel denies.

The Israeli onslaught followed an attack on Israel by Hamas on Oct. 7 that killed 1,200 with 250 people also taken as hostages, according to Israeli tallies.

Reuters