Unicef says over 13,000 children killed in Gaza

The UN children's agency said on Sunday that over 13,000 children had been killed in Gaza in Israel's offensive, adding that many children were suffering from severe malnutrition and did not "even have the energy to cry".

"Thousands more have been injured or we can't even determine where they are. They may be stuck under rubble… We haven't seen that rate of death among children in almost any other conflict in the world," Unicef's executive director, Catherine Russell, told CBS News' Face the Nation programme on Sunday.

"I've been in wards of children who are suffering from severe anaemia malnutrition, the whole ward is absolutely quiet. Because the children, the babies… don't even have the energy to cry."

Russell said there were "very great bureaucratic challenges" moving trucks into Gaza for aid and assistance.

A UN expert said earlier this month that Israel was destroying Gaza's food system as part of a broader "starvation campaign".