The toll in Gaza climbed to at least 90 Monday as Israel continued to strike targets within the Palestinian enclave. UN Secretary-General Ban Ki-moon headed to Egypt to attempt to secure a ceasefire.
Plumes of smoke rose across Gaza as Israel pummelled the city of 1.7 million from sea and air for a sixth straight day in response to a surge in Palestinian rocket fire earlier this month.
Gaza's health ministry said 91 Palestinians, many of them women and children, had been killed since Israel's military campaign began Nov 14. The Israeli Defense Forces put the figure at 95, with one third of the dead civilians.
Gaza health officials said 25 people were killed Monday, including three children.
"When Israeli forces strike a house, they destroy all the houses next to it," said north Gaza resident Sameh Alborai, 25, by telephone. "The Israelis are not warning anyone before they attack houses and have been targeting civilians from the first day."
Israeli Prime Minister Benjamin Netanyahu said last week that Israel was doing all it could to minimize civilian casualties as its military attacked what it says are "terrorist" targets in densely populated Gaza.
Three Israeli civilians have been killed since Nov 14 by rockets fired from Gaza, which has been ruled by the Hamas Islamist group since 2007.
UN chief Ban was expected to meet Egyptian President Mohamed Mursi in Cairo amid international attempts to end the violence.
Mursi, a member of the Muslim Brotherhood movement that gave rise to Hamas, warned last week that Egypt would not abandon Gaza.
Ban's visit to Cairo came as the radio station of the Israeli Defense Forces (IDF) reported that Israel had told Palestinian representatives via Egyptian mediators in Cairo that it would widen its operations if rocket attacks from Gaza did not cease.
Although Israel reported a dramatic drop in rocket attacks Monday, an IDF spokesperson tweeted later in the day that a Gaza missile had hit a school in the southern Israeli town of Ashkelon. The school had earlier been evacuated and there were no injuries.
The development came after Netanyahu warned Sunday that the Israeli military was prepared to "significantly expand" its military operation in Gaza.
"We will force Hamas and other terrorist organisations to pay a high price," Netanyahu told a Cabinet session. "The Israeli army is ready to significantly expand its operation."
Israel has put 75,000 reservists on stand-by and troops and military equipment are massed near the border with Gaza.
Hamas political leader Khaled Meshaal said Monday that Gaza was "standing steadfast in the face of Israel's machines of destruction".
"We are people of a just cause," he said at a Cairo news conference. "We are not aggressors against anyone. The Israelis are drowning in the blood of children."
Meshaal said if Israel wanted a truce, if would have to initiate the ceasefire, because it "started the war".
A Haaretz-Dialog poll taken Sunday indicated that 84 percent of the Israeli public supports the present military campaign, with 12 percent opposing it. But only 30 percent of the Israeli public would support a ground offensive in Gaza, the pollster reported.
US President Barack Obama reiterated Sunday Washington's insistence that Israel has the right to self-defence.
"There's no country on earth that would tolerate missiles raining down on its citizens from outside its borders. we are fully supportive of Israel's right to defend itself," said Obama.
But ordinary people in Gaza were scornful of Obama's comments.
"Since when does the occupier have the right to defend itself from the occupied?" asked Alborai. "Many people here believe Gaza is being attacked because of the Israeli elections that are coming up. Israel has an internal conflict and, like always in these situations, they are targeting Gaza."
Israel votes in parliamentary elections in January.
Turkish Prime Minister Tayyip Erdogan alleged Friday Israel's attack on Gaza was a pre-election ploy aimed at drumming up support for Netanyahu's Likud Party. On Monday, Erdogan labelled Israel a "terrorist state".
Netanyahu dismissed the accusations. "We are defending ourselves," he said.