UN Secretary General Antonio Guterres has made a renewed call for an immediate ceasefire in Gaza.
"It is time to silence the guns," he said, speaking from the Egyptian side of the Rafah crossing with the enclave.
He also called on Israel to give "total, unfettered" access to humanitarian goods throughout Gaza.
A UN-backed food security assessment this week said 1.1 million people in Gaza were struggling with catastrophic hunger and starvation.
It added that a man-made famine in the north was imminent between now and May.
Mr Guterres, who said he had come to Rafah "to spotlight the pain of Palestinians in Gaza", was speaking a day after Russia and China blocked a US draft resolution put to the UN which called for a ceasefire tied to the release of hostages held in Gaza.
"It's time to truly flood Gaza with life-saving aid. The choice is clear: either surge or starvation. Blocked relief trucks on the Egyptian side of border are a moral outrage," said Mr Guterres, who also called for the release of Israeli hostages.