Over 200 people were killed in under 24 hours by indiscriminate Israeli strikes on besieged Gaza, Gazan authorities confirmed on Saturday.

Despite growing calls for restraint and for more aid to reach war-stricken Palestinians, Israel showed little sign of modulating its 11-week-old "Operation Swords of Iron" – which aims to rout Hamas.

The attacks were now centered on Gaza City and the southern city of Khan Younis, both considered strongholds of the Palestinian resistance group, Hamas.

After reports of heavy Israeli shelling, grey and black smoke rose over the north of the coastal territory and in Khan Younis.

Outside a morgue at the city's Nasser Hospital, grieving relatives prayed, wept and stared vacantly as they tried to process incalculable loss.

Gazan authorities said the death toll from this war has now surged beyond 20,000.

"This is a genocide," said resident Rafat al Aydi.

Israel denies directly targeting civilians and says the war against Hamas is vital to ensure the October raids on farms, villages and kibbutzim that killed an estimated 1,140 people can never be repeated.

'We want a cease-fire'

In Washington, President Joe Biden said he had another "long talk" with Israel's hawkish prime minister, Benjamin Netanyahu.

The White House said the discussion focused on the "objectives and phasing" of Israel's military operation, as well as "the critical need to protect the civilian population including those supporting the humanitarian aid operations."

Israeli officials gave a terse readout of the call, saying "the Prime Minister made it clear that Israel would continue the war until all of its goals have been achieved".

On Friday, the United States allowed the passage of a U.N. Security Council resolution that effectively called on Israel to allow "immediate, safe and unhindered" deliveries of life-saving aid to Gaza "at scale."

World powers had wrangled for days over the wording, and at Washington's insistence toned down some provisions – including removing a call for a cease-fire.

U.N. Secretary-General Antonio Guterres has accused Israel of "creating massive obstacles" for aid deliveries.

For Palestinians in Gaza's southern city of Rafah, the prospect of aid alone was not enough.

"We don't want food, we want a cease-fire," said Mahmud al-Shaer.

Ahmad al-Burawi, who was displaced from Beit Lahia further north, added: "We just want to return to our lands, that's all. We want a solution" to end the war. "People are dying," he said.

The war has displaced about 80% of Gaza's 2.4 million population, according to U.N. estimates.