Israeli air raids brought the total death toll over four days to at least 100 people, at least a third of which have been children, according to medical sources.

Witnesses said Israeli aircraft attacked the office of Ismail Haniya, the ousted Palestinian prime minister, in Gaza City in the early hours of Sunday morning. No casualities were reported.

The UN Security Council went into emergency session on Saturday at the request of Abbas to discuss the bloody Israeli incursion into  the beleaguered Gaza Strip.

Israeli forces killed 61 people in the Gaza Strip on Saturday alone, the bloodiest day for Palestinians since an uprising against Israeli occupation began in 2000.

Khaled Meshaal, the exiled Hamas leader living in Syria, denounced the Israeli attacks against Gaza's civilians as "the real holocaust".

The Palestinian President Mahmud Abbas requested an emergency meeting of the UN Security Council to discuss the Israeli incursion into the Gaza Strip, a spokesman for the Palestinian leader said.

Marwan Bishara, Al Jazeera's senior political analyst, said that "at best" Abbas could hope to get a Security Council resolution condemning the Israeli action.

"And as we know, Israel has ignored tens of UN Security Council resolutions over the last 40 years and hundreds of UN assembly resolutions - so this is going to be more talk and probably not much will come out of it in the end," he said.

Children killed

Rana el-Hindi from Save the Children, speaking from inside the Gaza Strip, told Al Jazeera that children were suffering greatly from the Israeli bombardment.

"In the last three days at least 19 children have been killed ... it's a real concern for all organisations here," she said.

"Most of the time, when we go into the field and talk to the children about their fears and concerns, they are always afraid of a new [Israeli] invasion to the Gaza Strip - and obviously the current situation is just ... what they fear."

She said the number of children being hospitalised was increasing "day after day".

Eissam Younis, director of the Al Mizan Centre for Human Rights in Gaza, told Al Jazeera that the Israeli army was "intentionally and systematically targeting civilians" and criticised world powers for their muted response.

"Israel puts itself above the law because the international community is always silent," he said.

Israeli incursion

The main operation began before dawn on Saturday.

Israeli tanks, supported by helicopters, pushed into the town and refugee camp of Jabaliya in the northern Gaza Strip and continued the assault throughout the day.

More than 150 people were wounded in the operation, Dr Muawiya Hassanein, the head of Gaza's emergency services.

At least 16 of the Palestinians killed were fighters - including 13 from Hamas, two from Islamic Jihad and one from the Popular Resistance Committees.

Witnesses said many of the deaths in Jabaliya occurred as a result of gun battles between Palestinian fighters and Israeli soldiers.

Tariq Dardouna, a Palestinian resident trapped in his house in east Jabaliya, told Al Jazeera that Israeli forces were targeting civilians.

"The Israeli army opens fire at everything in our area, including children and houses. There are injured children bleeding inside their houses," Dardouna said.

Witnesses also reported clashes in the nearby Tufah neighbourhood in northern Gaza City.