US President Joe Biden speaks during an event. File photo

US President Joe Biden will make a landmark trip to Israel in an "ironclad" show of US support, as efforts to ease a spiralling humanitarian disaster in Gaza intensify.

Secretary of State Antony Blinken described the visit as a statement of "solidarity with Israel" and an "ironclad commitment to its security", just days after Hamas fighters broke through the heavily fortified border, shooting, stabbing and burning to death more than 1,400 people, most of them civilians.

But the air strikes have flattened entire neighbourhoods in the blockaded Gaza Strip and killed at least 2,750 people, most of them civilians.

The bombardment, coupled with an Israeli order to evacuate the north of the Gaza Strip that borders Israel, has forced more than a million Palestinians to flee their homes for the south of the enclave since the 10-day conflict began, according to the UN agency serving Palestinian agencies (UNRWA).

Biden's visit will also seek to avert a regional conflagration with Hamas backer Iran, which on Monday warned of a possible "pre-emptive action" against Israel "in the coming hours".

Repeated fire in recent days along Israel's northern border with Lebanon has claimed lives on both sides and compounded fears of a regional spillover of the war.

Antony Blinken

Biden's visit also comes amid frantic diplomatic efforts to ease the deepening humanitarian crisis in Gaza after waves of Israeli retaliatory air strikes on the Hamas-ruled enclave.

Meanwhile, World Health Organization regional director Ahmed Al-Mandhari told AFP that Gaza was barrelling toward "real catastrophe".

"There are 24 hours of water, electricity and fuel left" he said.

After Israel, Biden will travel to Jordan where he will meet Jordanian King Abdullah II, Palestinian leader Mahmud Abbas and Egyptian President Abdel Fattah Al Sisi.

Under relentless Israeli bombardment, thousands of Gazans have died and international agencies warn millions more face dwindling supplies of water, food and fuel -- even before a looming Israeli ground invasion.

From left: King Abdullah II, Mahmud Abbas, Joe Biden and Abdel Fattah Al Sisi. AFP

Prime Minister Benjamin Netanyahu and Israeli military leaders have signalled their intent to destroy Hamas and eradicate the threat it poses after the  group's attack which has been likened to 9/11.

Tens of thousands of regular Israeli troops and reservists have amassed at the border waiting for the order to go in.

An Israeli military spokesman said it was unclear how Biden's visit might change the timing of an Israeli ground offensive against Hamas in the Gaza Strip.

Several notable Hamas figures have already been killed in air strikes, including, on Monday, Osama Mazini, who the Israeli Air Force said was part of a top council and "responsible for Hamas prisoners."

Hamas is proscribed as a terrorist organisation by the United States and several other Western governments, while Israel has likened it to the Islamic State group.

International aid agencies have called for aid to urgently be allowed into the territory, and for Gaza's border with Egypt to be open to allow civilians to leave.

Agence France-Presse