A United Nations-backed panel has warned that famine is “imminent” in the Gaza Strip, days before a deadline imposed on Israel by the Biden administration to deliver more humanitarian supplies to the enclave or risk a cutoff of military aid.

The panel, the Integrated Food Security Phase Classification, said on Friday that 13 months of war had created “an imminent and substantial likelihood of famine” because of the “rapidly deteriorating situation in the Gaza Strip.”

The panel, which includes major relief agencies, warned that action was needed “within days, not weeks” to alleviate the immense suffering in the enclave. Last month, the panel said that conditions in Gaza had improved from May to August because of a surge of humanitarian assistance, but that the gains had largely been reversed since.

The Friday warning came less than a week before a deadline set by the Biden administration last month, when it demanded that Israel improve the flow of aid to Gaza’s 2.2 million residents. The administration warned that failure to provide more aid “may have implications for U.S. policy,” including on the provision of the military assistance upon which Israel depends.

“The amount of assistance entering Gaza in September was the lowest of any month during the past year,” said the letter, which was signed by Secretary of State Antony J. Blinken and Defense Secretary Lloyd J. Austin III. They asked that Israel take a series of concrete steps, including increasing the number of aid trucks permitted into Gaza each day “to reverse the downward humanitarian trajectory.”

Israel’s bombardment, siege and ground combat in Gaza has choked off food imports and destroyed the territory’s farmland and fishing industries. That has left nearly the entire population of Gaza reliant on scant humanitarian aid to survive.