Bloodshed in and around Gaza surged Tuesday with strikes killing 26 Palestinians, including at least four children, as Israel announced the deaths of five more soldiers, shattering hopes for an end to three weeks of violence.
It was a bloody start to the three-day Muslim holiday of Eid al-Fitr which began on Monday, with international demands for an end to the fighting falling on increasingly deaf ears.
"In the name of humanity, the violence must stop," pleaded UN Secretary General Ban Ki-moon after holding long talks with Israeli Prime Minister Benjamin Netanyahu, urging him to heed international calls for a ceasefire.
But Netanyahu appeared determined to press the offensive.
"We must be prepared for a lengthy campaign," he said in a live broadcast Monday.
"We will not end this operation without neutralising the tunnels whose sole purpose is killing our citizens."
As he spoke, the military sent messages to thousands of Palestinians in Shejaiya, Zeitun, Jabaliya, Beit Lahiya and Beit Hanun, urging them to flee their homes and seek shelter in central Gaza City as troops prepared to step up their 21-day campaign.
Shortly afterwards, the cloudy skies over Gaza lit up with flashes as the army began an intensive wave of air strikes and heavy shelling across the strip that continued early Tuesday and left 26 Palestinians dead, AFP correspondents and medics said.
Israeli warplanes hit the house of Hamas' top leader in Gaza, Ismail Haniya, inside Shati refugee camp, his son said Tuesday.
"The Israeli enemy struck our house twice," Abed Salam Haniya said in a statement. No one was hurt in the attack.
Also early Tuesday, eight rockets were fired at Israel, with two hitting the ground near Rishon LeZion, 10 kilometres (six miles) south of Tel Aviv.
The attacks were claimed by militants from the Ezzedine al-Qassam Brigades, the armed wing of Hamas.
- 'Eid of blood' -
Israel had stated five of its soldiers were killed Monday, but early Tuesday updated that toll to 10, saying that five of the soldiers died in clashes with a Palestinian commando who had tried to reach Israel through a tunnel at Nahal Oz, near the border with Gaza.
The deaths brought Israel's total death toll in the conflict to 53.
Since the start of Israeli military operations on July 8 at least 1,113 Palestinians have died.
"This is the Eid of the martyrs," said Ahed Shamali Monday, mourning the death of his 16-year-old son in Gaza.
His wife Abeer went further, telling AFP: "This is the Eid of blood."
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At the Shati refugee camp, eight children and two adults were killed and another 46 people injured on Monday.
The day had started with a deceptive air of calm in and around Gaza, following a quiet night in which both sides appeared to be observing an undeclared ceasefire.
Tensions rose sharply after medics said a shell had struck a building inside the Shifa hospital compound in Gaza City.
That was quickly followed by reports of a blast hitting a children's playground in the beachside Shati camp, which left 10 people dead, eight of them children.
Residents in Shati said an F-16 fired several missiles at a motorised rickshaw.
Near the site of the blast, women wailed and men screamed in anguish in scenes of utter confusion and distress, an AFP correspondent said.
The Israeli army categorically denied it had fired at either the hospital or the camp, blaming errant rocket fire by Palestinian militants.
"We have not fired on the hospital or on Shati refugee camp," Major Arye Shalicar told AFP, saying the only drones used near Shifa were not equipped with missiles.
"We know that Hamas was firing from both areas and the missiles struck these places," he said, adding that 200 missiles fired at Israel had fallen short and landed inside Gaza in the past three weeks.
- Fresh talks to be held in Cairo -
Shortly afterwards, a mortar shell struck southern Israel, killing four soldiers near a kibbutz opposite Gaza City, the army said. Another soldier died inside Gaza earlier Monday, accounting for the original five deaths announced by Israel Monday.
The strike was claimed by the Ezzedine al-Qassam Brigades, which said it was revenge for the deaths in Shati camp.
As the violence soared, top diplomats from Britain, France, Germany, Italy and the United States pledged to step up the pressure to force the sides to accept a truce.
A statement from the French presidency saying they had "agreed to redouble their efforts to obtain a ceasefire".
"Pressure must increase to get there," it said.
US Secretary of State John Kerry said any lasting truce must ensure the disarmament of Hamas and other militant groups, with parties working together on the basis of an Egyptian ceasefire initiative.
And Palestinian president Mahmud Abbas was expected to visit Cairo with representatives of Hamas and Islamic Jihad, another militant group, for fresh talks with the Egyptians on ending the violence in Gaza, a senior source in Ramallah told AFP.
North Korea, meanwhile, denied it was supplying missiles to Hamas in a foreign ministry statement carried by the official KCNA news agency.
It followed a weekend report by Britain's Daily Telegraph, citing Western security sources, that the Palestinian Islamist movement had already made an initial cash down payment to secure additional missiles from Pyongyang.