Eight Israeli human rights groups came together on Tuesday to demand the state investigate the army's behaviour in the deadly 22-day assault on the Gaza Strip.
They urged prosecutor general Menachem Mazuz, who is also the government legal adviser, to act "given the scale of the casualties among the civilian population during Operation Cast Lead."
A statement said the numbers of children and women killed were "terrifying."
It quoted Palestinian health ministry figures listing more than 1,300 people dead, including 410 children and about 100 women. Another 5,300 were wounded -- 1,855 of them children and 795 women.
"The rules of war seem to have been held in total contempt forcing Israel to open an independent inquiry immediately," the groups said.
"We call on the government legal adviser to act now to set up a mechanism for independent investigation."
The activists include B'tselem, the main Israeli rights body covering the occupied territories, Doctors for Human Rights, There is Justice and the Public Committee against Torture.
The groups noted Israeli civilians had been subjected to Palestinian rocket fire from the Gaza Strip -- "a serious violation of international law."
However, "this does not authorise Israel Another four UN buildings -- schools where Gazans were sheltering from the fighting -- were struck by Israel during the fighting. More than 40 people were killed in one such attack, according to medics and UN officials.
Israel has said it made very effort to prevent the deaths of civilians and said it was fired upon from inside or near each of the UN sites in question, a charge often disputed by UN workers.
Ten Israeli soldiers and three civilians were killed during the assault.