Staff and volunteers of Amnesty International USA, MoveOn, Oxfam America and Win Without War hold a vigil outside the White House calling for a Gaza ceasefire in Washington, US, on Monday. Reuters

Israel faced another round of global pressure on Tuesday for a ceasefire in Gaza with a new UN vote and fresh Western diplomatic efforts, although the United States vowed to continue arming its ally.

The UN Security Council was set to convene Tuesday to weigh a call for a ceasefire in the besieged Palestinian territory, after a previous bid was vetoed by the United States.

UK Foreign Minister David Cameron was also due to meet French and Italian leaders to push for a "sustainable ceasefire" in the conflict, his office said.

The Hamas-run health ministry in Gaza says Israel's military response has killed more than 19,400 people, mostly women and children.

Firefighters and civilians gather at the rubble of a building following Israeli bombardment in Rafah on Monday. AFP

The ministry said an Israeli strike killed at least 20 people on Tuesday in the southern city of Rafah, near the border with Egypt.

On a visit to Israel, US Defence Secretary Lloyd Austin vowed on Monday to keep arming its ally, which Washington has already provided with billions of dollars in military aid.

"We'll continue to provide Israel with the equipment that you need to defend your country... including critical munitions, tactical vehicles and air defence systems," Austin said.

Austin was touring the Middle East as concerns grew over the war's spread around the region, with Iran-backed Houthi rebels in Yemen attacking international shipping in the Red Sea in solidarity with Hamas.

US Secretary of Defence Lloyd Austin makes a statement in Tel Aviv on Monday. AP

Austin announced the formation on Monday of a 10-nation coalition to quell the rising number of Houthi attacks on tankers, cargo ships and other vessels in the Red Sea.

The coalition includes the United States, United Kingdom, Bahrain, Canada, France, Italy, Netherlands, Norway, Seychelles and Spain, Austin said.

In the latest incidents, Huthi rebels said Monday they had attacked two "Israeli-linked" vessels in the Red Sea.

Israeli protests

Israelis protested on Monday in central Tel Aviv, calling for swift action to release the remaining 129 hostages believed to be held in Gaza.

The anger and fear of hostages' families has intensified after Israeli forces mistakenly shot dead three captives who had escaped their captors.

Three Israeli hostages appear in footage by Hamas at a location given as Gaza. Reuters

Reports said the trio waved white flags and used food leftovers to write a Hebrew-language message on a white sheet before they were shot.

Hamas's military wing released footage it claimed showed three of those still held captive. The video featured three bearded men sitting on chairs at an undisclosed location and asking to be released.

The Gaza war has also seen violence spiral in the occupied West Bank.

Israeli forces shot dead four Palestinians in a West Bank refugee camp Monday, the Palestinian health ministry said, taking the toll in the occupied territory to over 300 during the Gaza war.

Agence France-Presse