WASHINGTON/GAZA CITY: US Secretary of State John Kerry is to push for an “immediate” ceasefire in Gaza when he arrives later Monday in Cairo, President Barack Obama said.

Obama also said that while Israel has the right to defend itself against a barrage of Hamas rockets, Washington has “serious concerns about the rising number of Palestinian civilian deaths and the loss of Israeli lives. “

“That is why it now has to be our focus and the focus of the international community to bring about a ceasefire that ends the fighting and that can stop the deaths of innocent civilians, both in Gaza and in Israel,” he said.

Kerry was headed to Egypt, which has been a mediator in past Israel-Palestinian conflicts and has taken the lead in trying to broker a truce between Israel and its foe Hamas, which dominates the Gaza Strip.

The two-week conflict has dramatically escalated in recent days, with Israeli ground forces pushing into Gaza, where the Palestinian death toll stood at 570 as of late Monday.

Obama noted that Israel had “already done significant damage to Hamas's terrorist infrastructure in Gaza.

“Eighteen Israeli soldiers have also died, the army's worst death toll in years.

“The work will not be easy,” Obama said of efforts to broker a ceasefire.

“Obviously, there are enormous passions involved in this, and some very difficult strategic issues involved,” the president added, in a statement delivered from the White House.

“Nevertheless, I've asked John to do everything he can to help facilitate a cessation to hostilities. We don't want to see any more civilians getting killed. “

Earlier, the United Nations demanded an “immediate ceasefire” in Gaza.

As world efforts to end the fighting gathered pace, Israel said it killed 10 Hamas militants in an early morning gun battle after they entered southern Israel through cross-border tunnels.

At an urgent meeting on Gaza, the UN Security Council urged an “immediate cessation of hostilities” in a call echoed by US President Barack Obama in a telephone conversation with Israeli Prime Minister Benjamin Netanyahu.

With growing concern over the number of civilian deaths, both US Secretary of State John Kerry and UN chief Ban Ki-moon headed to Cairo for ceasefire talks, which have so far been rejected by the Islamist Hamas movement.

Following the deadliest day in Gaza in more than five years, in which at least 140 Palestinians were killed, medics pulled another 45 bodies from the rubble early Monday, emergency services spokesman Ashraf al-Qudra said.

And 20 more people were killed in a series of strikes across Gaza.

In the latest incident, tank-shelling on a hospital in Deir al-Balah in central Gaza killed five people.

And a family of nine was killed in the southern city of Rafah, seven of them children, he said.

As the diplomatic efforts gathered steam, hundreds of people could be seen flooding out of the northern town of Beit Hanun, a day after many thousands fled an intensive Israeli bombardment of the eastern district of Shejaiya.

On Sunday, at least 72 people were killed in Shejaiya during a punishing Israeli operation which reduced much of the district to rubble and left charred bodies lying in the streets.

Militants infiltrate Israel

Since the Israeli operation began on July 8, huge numbers of Gazans have fled their homes, with more than 85,000 people taking shelter in 67 schools run by UNRWA, the UN agency for Palestinian refugees, a spokesman said.

By Monday morning, a UN school on the outskirts of Shejaiya was packed to overflowing with people seeking shelter, many sleeping in the corridors, an AFP correspondent said.

And in Gaza City's Shifa hospital, several families could be seen sleeping in gardens in the hope they would be safe from the bombing.

Israel’s TV channel retracts false allegations

Meanwhile, in southern Israel, the military said troops had killed “more than 10” Hamas militants who managed to cross the border through tunnels. It said there were “two terrorist squads,” one of which was hit by an air strike.

Military radio said the second squad engaged in a fierce gun battle with troops in which several soldiers were wounded, without giving further details.

On Sunday, 13 Israeli soldiers were killed inside Gaza, raising to 18 the total number of soldiers killed since a ground operation began late on Thursday.

That represented the army's heaviest losses in eight years and left Israel in mourning.

The attack was claimed by Hamas militants from the Ezzedine al-Qassam Brigades, which said it had carried out “an operation behind enemy lines in response to the massacre in Shejaiya”.

Late on Sunday, the Qassam Brigades claimed it had captured an Israeli soldier it named as Shaul Aaron in a report that the army said it was checking, but which Israel's UN ambassador said was untrue.

Ban's truce tour

As the UN chief sought to advance regional plans for a ceasefire, Kuwait's top diplomat pushed him to rally world support to end Israel's “dangerous aggression” in Gaza at talks in Kuwait City.

Ban was expected in Cairo later on Monday, ahead of the arrival of Kerry.

Elsewhere in the region, Hamas leader Khaled Meshaal was to meet Palestinian president Mahmud Abbas in the Qatari capital for talks on a ceasefire, officials said.

So far, ceasefire proposals have been rejected by Hamas, which has laid out a long list of demands it wants Israel to agree to, including an end to its blockade of Gaza and the release of scores of prisoners.

Despite rising concern over the number of civilian casualties, Netanyahu has blamed Hamas for using innocent civilians “as human shields” and insisted the military operation had “very strong support” from the international community.

Although Israel said Sunday it was expanding its ground operation to destroy cross-border tunnels, Defence Minister Moshe Yaalon suggested the mission could be accomplished within days.

There was no let-up in rocket and mortar fire by Gaza militants on Monday with 40 hitting Israel, one striking the greater Tel Aviv area, and another 11 shot down, the army said.