UN aid agencies have warned that "pockets of famine" already exist in Gaza, where thousands of people have been displaced by Israeli bombardments and left with little to no access to food.
In a joint statement, the World Food Programme, UNICEF and the World Health Organisation said new entry routes into Gaza must be opened in order to deliver humanitarian supplies.
While the UN did not directly blame Israel for hampering access to Gaza, the agencies said not enough trucks are being allowed through border checks each day.
They demanded fewer restrictions on the movement of humanitarian workers and the guaranteed safety of those accessing and distributing aid.
Living amid the ruins
In the north of Gaza, around 300,000 people are still living amid the ruins of buildings destroyed by Israeli strikes.
The UN says that delivering aid to them has been hampered by the continued fighting.
On Sunday, the UN said that less than a quarter of aid convoys had reached their destinations in the north in January because Israeli authorities denied most access.
Qatar and France aid deal
On Tuesday, Qatar and France announced they had brokered a deal with Israel and Hamas to deliver urgent medication to 45 hostages held in Gaza in return for humanitarian and medical aid for the most vulnerable civilians in the territory.
The aid is expected to leave Qatar for Egypt on Wednesday before being taken across the Rafah border crossing into Gaza.