Israel is “engineering chaos and massacres” in the Gaza Strip by continuing to block aid deliveries and opening fire on starving Palestinians seeking desperately needed food supplies, a humanitarian official has warned.

The Israeli military says it only targets militants and blames civilian deaths on Hamas because the militants operate in densely populated areas.

At least 67 people were killed by Israeli fire while they waited for U.N. aid trucks in northern Gaza on Sunday, the territory's health ministry said.