Sri Lanka, Feb. 26 -- A full-scale Israeli military operation in Rafah would deliver a death blow to aid programs in Gaza, where humanitarian assistance remains "completely insufficient," the UN chief warned Monday.

Speaking before the UN Human Rights Council in Geneva, Antonio Guterres said that Gaza's southernmost city, where more than 1.4 million Palestinians are crowded together in tent cities, was "the core of the humanitarian aid operation" in the Palestinian territory.

"An all-out Israeli offensive on the city would not only be terrifying for more than a million Palestinian civilians sheltering there; it would put the final nail in the coffin of our aid programs," he said.

His comments came after Israeli Prime Minister Benjamin ...