GAZA -- The head of the UN agency for Palestinian refugees accused Israel on Friday of deliberately causing famine in Gaza after international monitors confirmed that famine conditions have taken hold in the enclave.

"Months of warnings have fallen on deaf ears. Famine is now confirmed in Gaza City," Philippe Lazzarini, Commissioner-General of UNRWA, wrote on X. He said the crisis was"by design and man-made," blaming Israel for blocking food and other basic supplies, including UN aid, for months.

The Integrated Food Security Phase Classification (IPC), a network of U.N. agencies and NGOs, said famine had been confirmed in Gaza Governorate, which includes Gaza City, and was spreading south to Deir al-Balah and Khan Younis. It warned that by the end of September, nearly a third of Gaza's population -- more than 640,000 people -- could face catastrophic hunger, with another 1.14 million at emergency levels.

Lazzarini said the spread of famine could still be halted with a ceasefire and unrestricted humanitarian access.

Israel rejected the IPC findings. Prime Minister Benjamin Netanyahu's office called the report"an outright lie," saying Israel "does not have a policy of starvation" but rather "a policy of preventing starvation."

Gaza's Health Ministry said 273 people, including 112 children, have died from starvation and malnutrition since the war began.

Israel tightened its blockade on Gaza after the collapse of a ceasefire with Hamas on March 2, sharply curbing food, fuel, and humanitarian aid deliveries.