UN Secretary-General Antonio Guterres on Monday urged an immediate ceasefire in the Israel-Hamas conflict, as he warned that the bombarded Gaza Strip was becoming a “graveyard for children.”

“The unfolding catastrophe makes the need for a humanitarian ceasefire more urgent with every passing hour,” he told reporters at the UN headquarters.

“The parties to the conflict -- and, indeed, the international community -- face an immediate and fundamental responsibility: to stop this inhuman collective suffering and dramatically expand humanitarian aid to Gaza,” he said.

“The nightmare in Gaza is more than a humanitarian crisis. It is a crisis of humanity.”

Militants from Palestinian group Hamas stormed into Israel on October 7, killing some 1,400 people, mostly civilians, including through targeting homes and revelers at a music festival.

According to the health ministry in Hamas-run Gaza, 10,222 people, including more than 4,000 children, have been killed since Israel launched its retaliatory strikes on Gaza.

Guterres was formally launching a recently announced $1.2 billion UN humanitarian appeal to help 2.7 million Palestinians over the entire Gaza Strip and parts of the West Bank and East Jerusalem.

Aid trucks have been coming into Gaza from Egypt through the Rafah crossing, but the level remains well below the level before October 7, with Israel saying it needs time for security checks of vehicles, and they are not bringing fuel.

“Without fuel, newborn babies in incubators and patients on life support will die,” Guterres said.

“The way forward is clear. A humanitarian ceasefire -- now. All parties respecting all their obligations under international humanitarian law,” he said.

Guterres again voiced alarm about the “clear violations of international humanitarian law that we are witnessing.”

“Let me be clear: No party to an armed conflict is above international humanitarian law,” he said.

Guterres did not name Israel. He outraged Israel on October 24 at a Security Council meeting where he alleged violations of humanitarian law and said that the Hamas attacks “did not occur in a vacuum,” leading Israeli officials to accuse the UN chief of justifying violence.

Guterres denied that was his intention and on Monday repeated his condemnation of “the abhorrent acts of terror perpetrated by Hamas,” and urged the militants to free hostages taken on October 7.