UN chief Antonio Guterres, on a visit to the doorstep of Gaza, on Saturday said the world has seen enough of the war's horrors and appealed for a ceasefire to allow in more aid.

"Palestinians in Gaza -- children, women, men -- remain stuck in a non-stop nightmare," he said on the Egyptian side of the Rafah crossing where truckloads of aid trickle into Gaza but the population is stalked by "hunger and starvation".

"I carry the voices of the vast majority of the world who have seen enough," Guterres said, deploring "communities obliterated, homes demolished, entire families and generations wiped out".

He reiterated that "nothing justifies the horrific attacks by Hamas" against Israel, triggering the war on October 7

"And nothing justifies the collective punishment of the Palestinian people," the United Nations secretary-general said.

Guterres, speaking at a lectern in front of the imposing gates to the Gaza side of Rafah, through which aid trucks pass, said the "heartbreak and heartlessness of it all" were clear.

"A long line of blocked relief trucks on one side of the gates. The long shadow of starvation on the other," which he called "a moral outrage."

Guterres emphasised "it is more than time for an immediate humanitarian ceasefire" and appealed to Israel for "total, unfettered access for humanitarian goods throughout Gaza."

The UN chief, who makes an annual "solidarity mission" to distressed Muslim communities during their holy fasting month, said that "in the Ramadan spirit of compassion, it is also time for the immediate release of all hostages" captured in the October attacks and still held by militants in Gaza.