A United Nations agency says nearly fifty percent of those killed in Israeli strikes across the Gaza Strip are women and children.

So far Israeli aggression since December 27, has killed almost 700 Palestinians and wounded at least 3,100 others while many are feared to still be under the rubble.

Doctors in Gaza have also confirmed the report by The UN Office for the Coordination of Humanitarian Affairs (OCHA), saying that the main victims of Israeli strikes are civilians, many of whom are women and children. Thus far, over 200 children have been killed in Gaza.

Human rights organizations also expressed their grave concern over the mounting civilian casualties in Gaza after Israeli troops attacked a UN school in Jabalya where civilians had taken shelter.

At least 45 people were killed and dozens others injured in the attack, which Israeli officials tried to justify as an assault on a militant stronghold.

"The building was clearly waving a UN flag, there is no safe haven in Gaza. Look at what happened in Jabaliya yesterday," said Chris Gunness the spokesman for the UNWRA, the UN agency running the school.

UN Secretary General Ban Ki-moon also condemned the attack describing the act as "totally unacceptable."

"I am deeply dismayed that despite these repeated efforts, today's tragedies have ensued," Ban said, adding that "I call once again for an immediate ceasefire."