Israel's military denied striking a tent camp west of Rafah on Tuesday after Gaza health authorities said Israeli tank shelling had killed at least 21 people there, in an area Israel has designated a civilian evacuation zone.

Earlier, defying an appeal from the International Court of Justice, Israeli tanks advanced to the heart of Rafah for the first time after a night of heavy bombardment, while Spain, Ireland and Norway officially recognised a Palestinian state, a move that further deepened Israel's international isolation.

The United States, Israel's closest ally, reiterated its opposition to a major Israeli ground offensive in Rafah but said it did not believe such an operation was under way.

Describing the U.S. view of what would constitute a major offensive in Rafah, White House national security spokesperson John Kirby told reporters that it would involve "large numbers of troops in columns and formations in some sort of coordinated maneuver against multiple targets on the ground."

"That is a major ground operation," Kirby said. "We have not seen that."

Two days after an Israeli airstrike on another camp stirred global condemnation, Gaza emergency services said four tank shells on Tuesday hit a cluster of tents in Al-Mawasi, a coastal strip Israel designated as an expanded humanitarian zone where it advised civilians in Rafah to go for safety.

At least 12 of the dead on Tuesday were women, according to medical officials in the Hamas militant-run Palestinian enclave.

But Israel's military later said in a statement: "Contrary to the reports from the last few hours, the IDF (Israel Defence Forces) did not strike in the Humanitarian Area in Al-Mawasi."

Israel told around one million Palestinian civilians displaced by the almost eight-month-old war to evacuate to Al-Mawasi when it launched its incursion in Rafah in early May. Around that many have fled Rafah since then, the U.N. agency for Palestinian refugees UNRWA reported on Tuesday.

In central Rafah, tanks and armoured vehicles mounted with machine guns were spotted near Al-Awda mosque, a city landmark, witnesses told Reuters on Tuesday. The Israeli military said its forces continued to operate in the Rafah area, without commenting on reported advances into the city centre.

OUTRAGE

International unease over Israel's three-week-old Rafah offensive has turned to outrage after an attack on Sunday set off a blaze in a tent camp in a western district of the city, killing at least 45 people.

Israel said it had targeted two senior Hamas operatives and had not intended to cause civilian casualties. Israeli Prime Minister Benjamin Netanyahu has said the harm to civilians occurred when "something unfortunately went tragically wrong."

Global leaders voiced horror at the fire in a designated humanitarian zone of Rafah where families uprooted by fighting elsewhere had sought shelter, and they urged the implementation of a World Court order last week for a halt to Israel's assault.

After a meeting of the U.N. Security Council closed doors on Tuesday over the latest developments in Rafah, Algeria's U.N. Ambassador Amar Bendjama said the country would propose a draft council resolution to "stop the killing in Rafah."

The Israeli military said it was investigating the possibility that munitions stored near a compound targeted by Sunday's airstrike may have ignited and touched off the blaze.

The Biden administration said on Tuesday it was closely monitoring the probe into Sunday's air strike. U.S. Vice President Kamala Harris said: "The word tragic doesn't even begin to describe" what happened on Sunday.

But Kirby said there was nothing in the incidents on Sunday or on Tuesday that would prompt the United States to halt its military aid to Israel.

In a further blow to aid efforts, part of the U.S. military's pier off Gaza's coast broke off, probably due to bad weather, putting it out of operation temporarily, two U.S. officials said.

Saudi Arabia - which had been in talks to normalise relations with Israel before the war in Gaza erupted - on Tuesday accused Israel of committing "genocide massacres" by targeting Palestinian tents in Rafah, saying it held Israel accountable for its actions.

Egypt is again trying in tandem with Qatar and the U.S. to revive talks on a ceasefire and the release of hostages held by Hamas, but efforts have been hampered by Israel's assault on Rafah, Cairo's state-affiliated Al-Qahera News TV channel said on Tuesday, citing a senior official.

A person familiar with the issue said that Israel delivered its latest ceasefire and hostage release proposal to Qatar, and Qatar was to provide it to Hamas on Tuesday.

Hamas has said talks are pointless unless Israel ends its offensive in Rafah.

More than 36,000 Palestinians have been killed in Israel's offensive, Gaza's health ministry says. Israel launched its air and ground war after Hamas-led militants attacked southern Israeli communities on Oct. 7, killing around 1,200 people and seizing more than 250 hostages, according to Israeli tallies.

Israel says it wants to root out the last major intact formations of Hamas fighters hunkered down in Rafah and rescue hostages it says are being held in the area.