Israeli ground troops backed by tanks and warplanes swept into Gaza on a mission to stamp out rocket fire that the Hamas leadership said Friday was doomed to fail.
The deathtoll amongst Palestinians soared to 258 as the Israeli offensive entered its 11th day, with the army bombarding Gaza by air and sea as well as from tanks massed along the border.
Citing continued Hamas attacks, Israel said it was pressing ahead with an operation to destroy a network of tunnels riddling the Gaza strip, used for assembling rockets and staging cross border attacks.
Salvoes of rockets lit up the sky, and a seafront hotel in Gaza City housing scores of journalists shook violently with the force of the shelling, an AFP correspondent said.
The late Thursday assault followed a brief humanitarian truce and an urgent appeal by both Washington and the UN that Israel redouble its efforts to avoid harm to civilians.
"I regret that despite my repeated urgings, and those of many regional and world leaders together, an already dangerous conflict has now escalated even further," UN chief Ban Ki-moon told reporters, urging Israel to "do far more" to spare Palestinian civilians.
US Secretary of State John Kerry urged Israel to limit collateral damage in Gaza and be "precise" in its ground assault on the Palestinian enclave.
Kerry emphasised in a telephone call to Israeli Prime Minister Netanyahu "the need to avoid further escalation and to restore the 2012 ceasefire as soon as possible," a State Department statement said.
"Following 10 days of Hamas attacks by land, air and sea, and after repeated rejections of offers to de-escalate the situation, the Israel Defence Forces (army) has initiated a ground operation within the Gaza Strip," the army said.
Hamas said the ground operation was destined to fail.
"What the occupier Israel failed to achieve through its air and sea raids, it will not be able to achieve with a ground offensive. It is bound to fail," Hamas chief Khaled Meshaal from his exile in Doha.
A Hamas spokesman in Gaza earlier said "Israel will pay a high price" for launching the ground operation and that his Islamist movement "is ready for the confrontation".
Palestinian president Mahmud Abbas said Israel must stop its ground operation, warning it would lead to "more bloodshed" and complicate efforts to end the conflict in the enclave.
Israel approved the call-up of another 18,000 reservists, taking the total number approved to 65,000 for an operation aimed at protecting Israeli lives and striking "a significant blow to Hamas's terror infrastructure," the army said.
Shortly beforehand, the military began an intensive bombardment of Gaza by air and sea as well as by tanks massed along the border.
Salvoes of rockets lit up the sky, and a seafront hotel in Gaza City housing scores of journalists shook violently with the force of the shelling by sea, an AFP correspondent said.
Israel launched Operation Protective Edge on July 8 to stamp out rocket fire from Gaza, pounding the enclave from both the air and the sea.
Egypt lashed out at Hamas on Thursday, saying it could have saved dozens of lives had it accepted an truce brokered by Cairo but also condemned the "Israeli escalation."
"Had Hamas accepted the Egyptian proposal, it could have saved the lives of at least 40 Palestinians," said Egypt's Foreign Minister Sameh Shoukri.
An initial ceasefire proposal which was to begin on Tuesday was accepted by Israel but ignored by Hamas, which continued to fire rockets over the border.
- Targeting tunnels -
Netanyahu and Defence Minister Moshe Yaalon instructed the army "to commence ground action to strike at the terrorist tunnels from the Gaza Strip into Israeli territory," a statement from the premier's office said.
Army spokesman Major Arye Shalicar told AFP Israel's goal was "to strike Hamas infrastructure and operatives" in Gaza, including tunnels.
Experts have said a ground operation is the only way of reaching targets unattainable from the air, such as Hamas's network of tunnels.
Military spokesman General Moti Almoz urged Gaza residents to flee areas where the army was operating, warning that the ground campaign would "be extended as much as necessary."
Following an appeal by Washington and the UN, the military pledged to invest "unprecedented efforts" to limit harm to civilians.
On the ground, Palestinian witnesses reported gun battles breaking out east of the southern city of Khan Yunis, with military sources confirming it was one of the areas in which the troops were operating.
A military spokeswoman told AFP ground and air forces had attacked at least 36 targets in Gaza since the ground incursion began.
Since the operation was announced, seven Palestinians have been killed, including a five-month-baby, raising the overall death toll in Gaza to 248, medics said.
- Truce efforts -
After the ground operation began Thursday night, 16 rockets fired by Gaza militants hit Israel causing no injuries, with another 18 intercepted, the army said.
Military figures also show that 1,155 rockets fired from Gaza have hit Israel from July 8 to Friday, and another 312 shot down by the Iron Dome air defence system.
Ahead of the operation, an Israeli official told AFP a truce had been agreed with Hamas which was to have begun at 0300 GMT Friday.
But Hamas denied the claim, with spokesman Sami Abu Zuhri telling AFP the news was "incorrect."
Earlier on Thursday, Abbas met Egyptian President Abdel Fattah al-Sisi in Cairo as regional efforts to end the violence continued.
During the day, Gaza residents had enjoyed a short respite for the first time in 10 days as both sides agreed to respect a five hour humanitarian lull to allow for medical aid to be transported into Gaza and let people stock up on food and other essentials.