UN Secretary-General Antonio Guterres has called for aid to be allowed into Gaza immediately. The Egyptian-controlled Rafah crossing, the only route for goods that does not border Israel, is currently closed.

Guterres said, "We absolutely need to have these trucks moving as quickly as possible and as many as necessary."

Guterres said 2 million people in the Gaza Strip lack water, food, medicine and fuel. He said he is working with the relevant parties to clarify the conditions for the aid to cross the border.

Trucks loaded with supplies have formed a long line on the Egyptian side of the border. One of several reported sticking points is a disagreement over weapons inspections of the cargo. Israel has said it will allow the delivery of supplies as long as they do not benefit Hamas.

Gaza has come under fierce bombardment by Israeli troops. The conflict has killed more than 5,100 people on both sides.

Hamas leader Ismail Haniyeh called on Arabs and Muslims to use their Friday prayer gatherings to protest the attacks on the Gaza Strip.

Meanwhile, Israel has amassed tanks and artillery near Gaza. The defense minister has signaled that a ground offensive will begin shortly.