The Israeli military said it had called up an unprecedented 300,000 reservists and was imposing a total blockade on the Gaza Strip, in a sign it may be planning a ground assault in response to the devastating weekend attack by Hamas gunmen.
The latest death toll stands at 770 Palestinians in Gaza and more than 900 people in Israel, reports Al Jazeera.
Israel pounded Hamas targets in Gaza Tuesday and said the bodies of 1,500 Islamist militants were found in southern towns recaptured by the army in gruelling battles near the Palestinian enclave.
The EU's foreign policy chief Josep Borrell said he has invited the top diplomats from Israel and the Palestinian Authority to address an emergency meeting Tuesday of the bloc's foreign ministers.
Borrell said Israel's Foreign Minister Eli Cohen and Palestinian counterpart Riyad al-Maliki were asked to participate in the hybrid video and in-person talks after the surprise Hamas assault.
The World Health Organization called Tuesday for a humanitarian corridor to be established into and out of the Gaza Strip, which has been placed under total siege by Israel.
Israel's total siege of the Gaza Strip is banned under international law, the United Nations human rights chief said.
In a statement, UN High Commissioner for Human Rights Volker Turk condemned Israel's decision to order a "full siege" on Gaza, including the ban on food and water.
"We are faced with an explosive powder keg situation. We know how this plays out, time and time again – the loss of Israeli and Palestinian lives and incalculable suffering inflicted on both communities," he said.
Turk added that sieges that hurt the lives of civilians are "prohibited under international humanitarian law".
The Israeli military said on Tuesday that Hamas operatives had "nowhere to hide in Gaza" and that the air force was carrying out unprecedently intensive air strikes in the Palestinian enclave in waves every four hours.
"We will reach them (Hamas) everywhere," chief military spokesperson Rear Admiral Daniel Hagari said in a briefing.
The United Nations humanitarian office said on Tuesday that nearly 200,000 people or nearly a tenth of the population, have fled their homes in Gaza since the start of hostilities and is poised for shortages of water and electricity due to a blockade, says Reuters.
"Displacement has escalated dramatically across the Gaza strip, reaching more than 187,500 people since Saturday. Most are taking shelter in schools," Jens Laerke, OCHA spokesperson, told a Geneva briefing, saying further displacement was expected as clashes continue.
Israeli air operations have struck residential buildings, including large tower blocks, as well as schools and UN buildings across Gaza, resulting in civilian casualties, the United Nations Human Rights chief has said, citing information gathered by his office.
"International humanitarian law is clear: the obligation to take constant care to spare the civilian population and civilian objects remains applicable throughout the attacks," Volker Turk said in a statement.
The Euro-Med Human Rights Monitor has accused Israeli forces of "mass killing crimes against civilians" in Gaza, says Al-Jazeera.
"The Israeli forces are taking revenge on Palestinian armed factions by committing mass killing crimes against civilians," the group said of Israel's relentless bombardment of densely populated areas, as it posted a photo on social media of a levelled neighbourhood.
"Even in cases of military necessity, Israel must adhere to provisions of international humanitarian law in its attack on Gaza."
