President Joe Biden has warned Israel that the US will stop supplying some weapons if it launches a major ground operation in the Gaza city of Rafah.

"If they go into Rafah, I'm not supplying the weapons that have been used historically to deal with Rafah," he said during an interview with CNN.

He added that he would "continue to make sure Israel is secure".

Despite firm and vocal US opposition, Israel appears poised to mount a large-scale invasion of Rafah.

The congested part of southern Gaza is Hamas's last major stronghold in the territory. US officials have warned that an operation in the city - where the population has swelled with refugees from other parts of Gaza - could lead to extensive civilian casualties.

"We're not going to supply the weapons and artillery shells," Mr Biden said in the interview, which aired on Wednesday.

He said the US did not define the current situation in Rafah as a ground operation. "They haven't gone into the population centres. What they did is right on the border," he said.

"But I've made it clear to [Israeli Prime Minister Netanyahu] and the war cabinet, they're not going to get our support, if in fact they go in these population centres."

Mr Biden acknowledged that US weapons had been used by Israel to kill civilians in Gaza.

When asked if Israel had crossed a "red line", the US president replied "not yet".

The comments amount to the president's strongest warning yet over a potential ground invasion of Rafah, and mark the first time he has said the US could stop shipments of American weapons to Israel.

Israel's ambassador to the UN said the country was "very disappointed" by Mr Biden's intervention.

"This is a difficult and very disappointing statement to hear from a president to whom we have been grateful since the beginning of the war," Gilad Erdan told Israeli public broadcaster Kan radio.

The US has already delayed a shipment of thousands of bombs to Israel, and has said it is reviewing future deliveries.

On Wednesday, Defence Secretary Lloyd Austin confirmed the delay of the bomb shipment - some of the most destructive munitions in Western military arsenals - while testifying in front of the Senate.

The weapons being held back by the US are related to a future delivery, so the move is unlikely to have an immediate impact. But given the rate at which Israel is bombing it will probably affect future strikes fairly soon.

The Israeli military, meanwhile, has said that the two countries will resolve disagreements "behind closed doors".

President Biden faces mounting domestic pressure - from some Democrats and parts of the US public - to rein in Israeli operations in Gaza amid rising civilian deaths and a worsening humanitarian situation.

US officials confirmed that no new aid supplies had been delivered in Gaza via two gates in the south since Israeli tanks rolled into southern Rafah and took control of the Palestinian side of the crossing with Egypt this week.

Israeli military spokesman Daniel Hagari said the US had provided "unprecedented" security assistance since the beginning of the war, adding that disputes between the allies were resolved "behind closed doors in a matter-of-fact way".

But a leading member of Mr Netanyahu's Likud party in Israel told the BBC's Newshour on Wednesday he believed US domestic political considerations were behind the decision to halt the delivery of bombs.

"I totally disagree that the American election has nothing to do with it," said Boaz Bismuth, a member of both the Israeli parliament and the foreign affairs and defence committee.

Rafah has been a key entry point for aid, and the only exit for people able to flee, since the start of the war between Israel and Hamas last October.

The crossing remained closed on Wednesday morning, but the Israeli military said it was reopening the nearby Kerem Shalom crossing, which had been closed for four days because of Hamas rocket fire.

On Monday, the Israeli military ordered tens of thousands of civilians to begin evacuating eastern parts of Rafah city, ahead of what it called a "limited" operation to eliminate Hamas fighters and dismantle infrastructure.

Meanwhile, efforts continue to reach a ceasefire, alongside the release of Israeli hostages and Palestinian prisoners. In Cairo, delegations from Israel and Hamas have resumed negotiations through mediators.

A US official said that talks with Israel were "ongoing and have not fully addressed our concerns" and the US had been reviewing its weapons transfers to Israel since April.

Israel launched a campaign to destroy Hamas in response to the group's attack on southern Israel on 7 October, during which about 1,200 people were killed and 252 others were taken hostage, according to Israeli tallies.

More than 34,780 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.

A deal agreed in November saw Hamas release 105 hostages in return for a week-long ceasefire and some 240 Palestinian prisoners in Israeli jails. Israel says 128 hostages are unaccounted for, 36 of whom are presumed dead.