Smoke rose from strikes on Gaza's crowded southern city of Rafah Thursday after US President Joe Biden vowed to cut off artillery shells and other weapons supplied to Israel if a full-scale offensive into the city goes ahead.
It was the starkest warning yet from Israel's main military provider over the civilian impact of its war against Hamas Palestinian militants.
An AFP correspondent and witnesses on Thursday reported strikes on several parts of Rafah, where the United Nations said 1.4 million people were sheltering.
"The tanks and jets are striking," Tarek Bahlul said earlier on a deserted Rafah street. "Every minute you hear a rocket and you don't know where it will land."
Israel has already defied international objections by sending in tanks and conducting what it called "targeted raids" in the eastern area of Rafah, the city it says is home to Hamas's last remaining battalions.
In an interview with CNN on Wednesday, Biden warned he would stop some US weapons supplies to Israel if it pushed ahead with its long-threatened major Rafah ground offensive.
Israel on Thursday called Biden's comments "very disappointing".
Biden told CNN that, "If they go into Rafah, I'm not supplying the weapons that have been used... to deal with the cities." He added: "We're not gonna supply the weapons and the artillery shells that have been used."
When asked about Israel's action already in Rafah, Biden said "they haven't gone in the population centres".
The fresh warning came after his administration paused delivery last week of 1,800 2,000-pound (907 kilogram) bombs and 1,700 500-pound bombs as Israel appeared ready to attack Rafah.
"Civilians have been killed in Gaza as a consequence of those bombs," Biden said. "It's just wrong."
Ties between the allies have become increasingly strained as Biden and other top Washington officials criticise Israel over its conduct of the war.
Pro-Palestinian protests have flared at universities across the United States and around the world with an intensity not seen for decades.
The war in Gaza began with Hamas's unprecedented October 7 attack on Israel, which resulted in the deaths of more than 1,170 people, mostly civilians, according to an AFP tally of Israeli official figures.
During their October attack militants seized Israeli and foreign hostages, of whom Israel estimates 128 remain in Gaza, including 36 who the military says are dead.
Israel in response vowed to crush Hamas and free the captives. It began a military offensive that has killed at least 34,904 people in Gaza, mostly women and children, according to the Hamas-run territory's health ministry.
The ministry on Thursday reported at least 60 more deaths over the previous 24 hours. Since Monday when Israel ordered residents of eastern Rafah to evacuate, the daily reported toll has been above 50, up from a peak of 33 earlier in May.
The United Nations agency for Palestinian refugees, UNRWA, on Thursday said 80,000 people have fled Rafah since Monday, but "nowhere is safe".
On Tuesday Israel seized Rafah's border crossing into Egypt, which has served as the main entry point for aid into besieged Gaza.
The White House condemned the aid disruption, and the defence secretary later confirmed Washington had paused the bomb shipment.
In Israel's first reaction to Biden's threat, its ambassador to the United Nations, Gilad Erdan, called it a "very disappointing statement".
"If Israel is restricted from entering an area as important and central as Rafah where there are thousands of terrorists, hostages and leaders of Hamas, how exactly are we supposed to achieve our goals?" he said on public radio.
Ari Tolany, who follows the arms trade for the progressive Center for International Policy, doubted the halt would have "an immediate operational impact" but said it sent a message to Israel not to drop 2,000-pound bombs, as it already has in the war.
The Israeli military said Wednesday it was reopening another major aid crossing into Gaza, Kerem Shalom, as well as the Erez crossing into north Gaza.
But it was unclear if aid was entering the territory where, according to the World Food Programme's chief, famine has already begun.
UNRWA said the Kerem Shalom crossing -- which Israel shut after a rocket attack killed four soldiers on Sunday -- remained closed.
Late Wednesday, the army said a soldier was lightly wounded when rockets again targeted the Kerem Shalom area.
The Hamas authorities' "emergency committee" in Rafah said Thursday that Israel's "control of the Rafah crossing and its closure, along with the halt of aid and fuel supplies, threatens to exacerbate the humanitarian, environmental, and health catastrophe."
The committee dismissed as "nothing but lies" Israel's description of its Rafah operation as "limited".
The World Health Organization on Wednesday said hospitals in southern Gaza had only three days of fuel left.
Fuel is critical to aid operations, not only for powering hospital equipment but also enabling aid workers to move, and to keep bakeries running, said Rik Peeperkorn, the WHO representative in the Palestinian territories.
Mazen al-Shami, speaking among metal trailers where some families had set up a small refugee camp in Rafah, said she was fed up.
"We have no money and we don't have the means to move from one place to another again and again. We have no means at all," Shami said.
Talks involving Qatari, US and Hamas delegations aimed at cementing a long-stalled ceasefire deal would continue Thursday in Cairo, said Al-Qahera News, which is linked to Egyptian intelligence.
It added, citing an informed source, that Islamic Jihad, which is fighting alongside Hamas, and the Marxist Popular Front for the Liberation of Palestine, were also participating and "are open" to reaching a deal.
Al-Qahera said efforts were underway to "iron out points of contention in the negotiations".
