Guterres made the appeal on Tuesday, as more than 100 sick and injured Palestinians congregated at the newly reopened Rafah crossing between Gaza and Egypt, hoping to access medical care abroad.

“I also call for the facilitation of rapid and unimpeded passage of humanitarian relief at scale – including through the Rafah crossing,” Guterres said during an address at UN headquarters in New York.

Reporting from southern Gaza’s Khan Younis, Al Jazeera’s Hind Khoudary said only 16 Palestinians were allowed to cross into Egypt via Rafah on Tuesday. A day earlier, only five people were permitted to leave, while 12 were allowed back into Gaza.

That is far below the 50 Palestinians who Israeli officials said would be allowed to travel in each direction via the crossing.

“There is no explanation as to why crossings are being delayed at Rafah,” Khoudary said. “The process is taking an extremely long time.”

She added that Palestinians have been forced to leave all their belongings when passing through the crossing, which until Monday had been mostly closed for nearly two years during Israel’s genocidal war against Palestinians in Gaza.

“There are about 20,000 people waiting [in Gaza] for urgent medical attention abroad,” Khoudary said.

Meanwhile, Israeli forces shot and killed a 19-year-old Palestinian near Khan Younis, despite a purported “ceasefire” deal that entered into force in October.

Gaza’s Nasser Hospital said the man was shot in an area away from where the Israeli military has seized total control.

His death brings the number of Palestinians killed in Israeli attacks on Gaza since the start of the “ceasefire” in mid-October to 529, according to the enclave’s Health Ministry.

Most of Gaza’s hospitals and medical infrastructure were obliterated in Israel’s genocidal war, leaving seriously injured and chronically ill patients with little recourse inside the territory.