From the article:

Military operations in Rafah could lead to a slaughter in Gaza. They could also leave an already fragile humanitarian operation at death’s door," said U.N. aid chief Martin Griffiths. "We lack the safety guarantees, the aid supplies and the staff capacity to keep this operation afloat.
“The international community has been warning against the dangerous consequences of any ground invasion in Rafah. The Government of Israel cannot continue to ignore these calls,” he said in a statement.

Talks involving the U.S., Egypt, Israel and Qatar on a Gaza truce ended without a breakthrough on Tuesday as calls grew for Israel to hold back on its planned Rafah assault.
“My sincere hope is that negotiations for the release of hostages and some form of cessation of hostilities to be successful to avoid an all-out offensive over Rafah,” U.N. Secretary-General Antonio Guterres told reporters on Tuesday.

“That would have devastating consequences,” he said.
The war in Hamas-run Gaza began when Hamas militants attacked Israel on Oct. 7, killing 1,200 people and capturing 253 hostages, according to Israeli tallies. In retaliation, Israel launched a military assault on Gaza that health authorities say has killed more than 28,000 Palestinians with thousands more bodies feared lost amid the ruins.

More than half Gaza’s 2.3 million people are sheltering in Rafah, many of them penned up against the border fence with Egypt and living in makeshift tents. Griffiths said they are “staring death in the face.”

“They have little to eat, hardly any access to medical care, nowhere to sleep, nowhere safe to go,” he said. “I have said for weeks now that our humanitarian response is in tatters.”