UN Secretary-General António Guterres reiterated his call for an immediate ceasefire in Gaza.
“It's time to silence the guns,” he said from the Egyptian side of the Rafah River, which intersects the enclave.
He also called on Israel to give “full and free” access to humanitarian supplies across Gaza.
A United Nations-backed food security assessment this week found that 1.1 million people in the Gaza Strip are suffering from devastating hunger and starvation.
He added that man-made famine was imminent in the north between now and May.
Guterres said: “The time has come to actually deliver life-saving aid to Gaza. The choice is clear: population boom or famine. It is morally outrageous to block the passage of relief vehicles on the Egyptian side of the border.'' He also called for the liberation of people. hostage.
“What I want Palestinians in Gaza to know is that you are not alone. People all over the world are outraged by the horrors we are all witnessing in real time.Palestinians in Gaza They are still trapped in an unstoppable nightmare.”
The Rafah crossing is one of the main entry points for aid into Gaza, with long lines of aid-laden trucks waiting for Israeli permission to cross.
Western countries and aid groups have criticized Israel over its inspection process, saying it is delaying the entry of much-needed aid.
Israel denies it is withholding humanitarian aid and says inspections are needed to ensure Hamas does not divert aid.
The war in Gaza began on October 7 when Hamas militants attacked southern Israel, killing about 1,200 people and taking 253 hostages.
The Hamas-run health ministry said more than 32,000 Palestinians had been killed in Israeli retaliatory airstrikes and continued ground attacks.
Earlier, Guterres met with UN humanitarian workers in El Arish, the Egyptian city closest to Gaza, where much of the international aid to the enclave has been delivered and stockpiled. He then visited a hospital where injured Palestinians were being treated.
His visit comes as Israel plans to launch ground operations in Rafah. More than half of Gaza's 2.3 million Palestinians have fled to southern cities, where Israel says Hamas leaders are in hiding and Hamas battalions remain active.
Israeli Prime Minister Benjamin Netanyahu ignored international criticism of the planned attack, saying “no international pressure can deter Israel” and insisting on achieving all of the war's objectives. .