The Israeli military also called on residents and displaced people in the Jabalia area of northern Gaza to clear out, saying it was returning to operate there after it noticed Hamas trying to re-establish its control of the area.
The Palestinian health ministry said at least 37 Palestinians, 24 of them from central Gaza areas, were killed in overnight airstrikes across the enclave, including in Rafah, the Strip's southernmost city bordering Egypt. It does not distinguish how many were civilians or militants.
"They threw fliers on Rafah and said, from Rafah to al-Zawayda is safe, people should evacuate there, and they did, and what has become of them? Dismembered bodies? There is no safe place in Gaza," Khitam Al-Khatib, who said she had lost at least 10 of her relatives in an airstrike on a family house earlier on Saturday, told Reuters.
Al-Zawayda is a small town in central Gaza Strip that has been crowded by thousands of displaced people from across the enclave.
The Israeli military said its aircraft struck tens of targets across Gaza over the past day, adding its ground troops had eliminated some 30 fighters in Zeitoun.
An Israeli airstrike killed at least seven people in a house in Beit Lahiya town in the northern Gaza Strip, all from the same family, medics said. Residents said Israeli tanks have been stationed in the town.
In Rafah, where the health ministry said 16 people were killed, residents told Reuters the new evacuation orders by the Israeli military covered areas in the centre of the city and left little doubt Israel planned to expand its ground offensive there.
"The situation is very difficult, people are leaving their homes in panic," said Khaled, 35, a resident of the Shaboura neighbourhood, an area where the new orders to leave have been issued.
The Israeli military said it was continuing operational activity against Hamas fighters in eastern Rafah and on the Gazan side of the Rafah crossing.
RAFAH INCURSION
Despite heavy US pressure and alarm expressed by residents and humanitarian groups, Israel has said it will proceed with an incursion into Rafah, where more than 1 million displaced people have sought refuge during the seven-month-old war.
Israeli tanks captured the main road dividing Rafah's eastern and western sections on Friday, effectively encircling the eastern side in an assault that has caused Washington to hold up the delivery of some military aid to its ally.
Israel says it cannot win the war without rooting out thousands of Hamas fighters still deployed in Rafah.
The war was triggered by a Hamas-led attack on southern Israel on Oct. 7 in which some 1,200 people were killed and more than 250 people taken hostage, according to Israeli tallies.
Israel's military operation in Gaza has killed close to 35,000 Palestinians, according to Gaza's health ministry. The bombardment has laid waste to the coastal enclave and caused a deep humanitarian crisis.
Two crossing points vital for delivery of aid to Gaza were still closed on Saturday. The Palestinian WAFA news agency said the Rafah crossing from Egypt was closed for a fifth day, while another crossing, Kerem Shalom from southern Israel, has been shut for around a week.
The latest evacuation orders came hours after internationally mediated ceasefire talks appeared to be faltering. Hamas said Israel's rejection of a truce offer it had accepted returned things to square one. Israel said the terms did not meet its demands.
The Palestinian militant group also hinted it was reconsidering its negotiation policy. It did not elaborate on whether a review meant it would harden its terms for reaching a deal, but said it would consult with other allied factions.
Israel says it wants to reach a deal under which hostages would be released in exchange for the freeing of Palestinian prisoners held by Israel, but that it is not prepared to end the military offensive.
'EXHAUSTED'
In Deir Al-Balah in the central Gaza Strip, where hundreds of thousands were sheltering, Palestinians mourned relatives during funerals on Saturday.
"Here they are, in pieces, here is my sister-in-law, without a head, my aunt is without a head, what is this injustice? Until when will this go on? We are exhausted, by God we are exhausted, I have lived in tents for the past seven months," said Khatib, sitting near bodies wrapped in white shrouds bearing the names of the dead men and women.
Prime Minister Benjamin Netanyahu's government is under increasing pressure over its military campaign, including from longtime ally the United States.
The Biden administration said on Friday Israel's use of US-supplied weapons may have violated international humanitarian law during its Gaza operation, in its strongest criticism to date of Israel.
But the administration stopped short of a definitive assessment, saying that due to the chaos of the war it could not verify specific instances where use of those weapons might have been involved in alleged breaches.
