At least 46 Palestinians and two Israeli soldiers have been killed in one of the deadliest days of fighting in Gaza since troops withdrew in 2005.
Medical staff said at least eight were children and up to 16 were militants. Israel said most were militants. Seven Israeli troops were lightly injured.
Israel says it wants to stop rocket attacks from Gaza, but about 50 hit Israel on Saturday, injuring five.
The Palestinian leader has demanded urgent UN Security Council talks.
Mahmoud Abbas said the Israeli raids were "more than a holocaust".
He was apparently alluding to controversial remarks made on Friday by Israel's Deputy Defence Minister Matan Vilnai, who said Palestinians risked a "shoah" - the Hebrew word for a big disaster as well as for the Nazi Holocaust.
Mr Vilnai's colleagues insisted he had not meant "genocide".
Khaled Meshaal, Hamas' exiled leader in Syria, went further, calling Israel's actions "the real Holocaust".
Civilian deaths
Israel has said it may launch a full-scale attack on Gaza in response to militant rocket attacks.
The BBC's Katya Adler in Jerusalem says Israel's leaders have been under pressure from some quarters to launch a ground invasion.
However, a recent opinion poll has indicated a majority of Israelis favour a truce with the Islamist movement Hamas, which controls Gaza.
Israeli government spokesman David Baker said "Israel is compelled to take the proper steps to bring an end to these rocket onslaughts" on about 200,000 Israelis living alongside Gaza's border.
Tanks and troops have made an incursion into northern Gaza, encountering resistance from Palestinian militants, as Israeli planes made several air raids.
On one occasion, a house east of the Jabaliya refugee camp was struck - two children, a brother and sister, were killed.
Later, a 15-year-old girl and her 16-year-old sister were also killed.
In another attack, a mother was killed as she was preparing breakfast for her children, medical workers said.
"We are in the middle of a total war. We hear the rockets and the explosions everywhere... we cannot leave our homes," a Jabaliya resident, Abu Alaa, told the AFP news agency.
"They're shooting at everything that moves."
There was also fighting in and around the camp between Israeli troops backed by tanks and Palestinian militants equipped with crude rockets and mortars.
Israel says its aim is to stop Palestinian militants firing rockets across the border.
On Wednesday a rocket fired by Hamas militants killed an Israeli student in the southern town of Sderot, the first such death in nine months.
Palestinian militant leaders say they are responding to Israeli attacks.
More than 70 Palestinians have been killed in the violence since Wednesday.
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Source: http://news.bbc.co.uk/go/pr/fr/-/2/hi/middle_east/7272329.stm 
