Israel bombarded Gaza on Saturday after accusing Hamas of destroying a humanitarian ceasefire by capturing a soldier whom the Islamists say was probably killed in Israeli shelling.
As the conflict raged into a 26th day following the collapse after only two hours of the truce, a top-level Palestinian delegation was due in Cairo for talks on a permanent ceasefire agreement.
The team, which would include senior members of Hamas and Islamic Jihad, was to arrive mid-afternoon for talks with Egyptian officials.
It was not immediately clear whether an Israeli team would also participate, with a decision expected on that Saturday evening, an official told AFP.
But the chances of the sides halting fire seemed remote after Israel said it believed militants had captured a 23-year-old soldier in a Friday morning ambush near the southern Gaza city of Rafah.
Immediately afterwards, Israel began intensely bombing the Rafah area in shelling that is still ongoing, with medics saying it killed 114 people in 24 hours, 57 of them since midnight (2100 GMT Friday).
The violence raised the overall death toll in Gaza to 1,654, the vast majority of them civilians, medics said, with the number of wounded at more than 8,900.
The alleged capture of Second Lieutenant Hadar Goldin drew sharp condemnation from the United Nations and the White House, who had jointly brokered the abortive 72-hour truce, and who demanded he be immediately released.
Israel has said it believes Goldin was snatched in an ambush that involved a suicide bomber, who killed two other soldiers, and has placed the blame squarely on Hamas.
- 'No knowledge of missing soldier' -
Hamas's armed wing, the Ezzedine al-Qassam Brigades, acknowledged its militants had staged an ambush early Friday in which soldiers were killed, but denied holding the missing man, saying the attackers were missing and presumed dead.
"At 7:00 am on Friday, our mujahedeen started an exchange of fire with the occupation forces... east of Rafah, and a lot of Israeli soldiers were killed and injured," the group said.
"We have lost contact with the mujahedeen unit that was in that ambush, and we think that all the fighters in this unit were killed by Zionist shelling along with the soldier, who the enemy says is missing, assuming our combatants captured this soldier during the fighting," it said.
"Until now, we in Qassam have no knowledge of the missing soldier, or his whereabouts or the circumstances of his disappearance."
Israel said it was focusing its search for Goldin on the outskirts of the sprawling city of Rafah, an area home to some 210,00 Palestinians.
Army spokesman Lieutenant Colonel Peter Lerner said "our understanding is that the force was attacked by a suicide bomber, (but it) seems there were several other gunmen who carried out this attack," and that Goldin had been "snatched into a tunnel."
Israel considers the capture of its soldiers a casus belli.
In 2006, Gaza militants captured conscript Gilad Shalit and held him for five years before freeing him in exchange for more than 1,000 Palestinian prisoners.
Weeks after Shalit's capture, Israel launched a 34-day war on the Hezbollah militia in Lebanon after it seized two soldiers, whose remains were later returned in another swap deal.
US President Barack Obama "unequivocally condemned" the killing of two soldiers and the lieutenant's alleged capture, saying that if those responsible wanted an end to the bloodshed, Goldin would need to be "unconditionally released, as soon as possible".
"I think it's going to be very hard to put a ceasefire back together again if Israelis and the international community can't feel confident that Hamas can follow through on a ceasefire commitment," he said.
Meanwhile, air strikes and tank fire pounding huge areas of Gaza into rubble and rendered much of it unrecognisable to one Palestinian who returned home after spending years in an Israeli jail.
"It was my dream to return to Gaza but it is a real shock," said 30-year-old Osama who comes from the central town of Deir al-Balah.
"Everything has been destroyed."
Since Friday, more than 400 houses have been levelled across Gaza, mostly by air strikes, Palestinian officials said.
And UN figures show that up to 25 percent of Gaza's population of 1.8 million may have been forcibly displaced, with more than a quarter of a million people now seeking safety in shelters belonging to UNRWA, the UN agency for Palestinian refugees.
- Egypt offers 'concrete solution' -
Despite the collapse of the ceasefire initiative, Palestinian president Mahmud Abbas is leading a delegation to Cairo for talks that his Egyptian counterpart said can offer a solution to the spiralling violence.
"Abbas has formed the delegation, which will head Saturday for Cairo whatever the circumstances," his office said Friday of the 12-member group.
The delegation includes Abbas aide Azzam al-Ahmed, Palestinian intelligence chief Majid Faraj; several senior Hamas officials, including Mussa Abu Marzuq, and a leading Islamic Jihad member, Ziad al-Nakhale.
Ahead of the meeting, Egypt's President Abdel Fattah al-Sisi said a truce proposal by Cairo "is the real chance to find a solution to the crisis in Gaza and to end the bloodshed".
"Time is decisive, we have to take advantage of it quickly to douse the fire in the (Gaza) Strip... and to stop the bloodshed of Palestinians," he told a news conference.