Displaced Palestinian children holding pots and pans wait in line as volunteers distribute a hot meal in Khan Yunis in the southern Gaza Strip on November 23, 2023. AFP
The WFP said it had delivered food to 121,161 people in Gaza since Friday, when a four-day truce between Israel and Hamas began.
The truce was extended by two days on Tuesday.
"Thanks to the pause, our teams have been in action on the ground, going into areas we haven't reached for a long time. What we see is catastrophic," said WFP's director for the Middle East, Corinne Fleischer.
WFP estimated that it was "highly likely that the population of Gaza, especially women and children, are at high risk of famine if WFP is not able to provide continued access to food".
The agency said that six days was "not enough to make any meaningful impact", calling for "uninterrupted and regular supplies" of food into Gaza.
In Gaza, WFP has reached 759,082 people with food and vouchers since the start of the crisis.
The truce paused fighting that began on October 7 when Israeli officials claim that Hamas movement took around 240 captives and killed 1,200 people in the deadliest attack in the country's history.
In response, Israel has vowed to "crush" Hamas and initiated a lethal and barbaric air, sea and ground invasion against the civilians in the Gaza Strip.
The Palestinian health ministry reports that nearly 15,000 people, two-thirds of them women and children, have been killed by the Israeli offensive on Gaza.
* This story was edited by Ahram Online.