GENEVA - The United Nations, which has warned of famine in Gaza, said on Wednesday the amount of humanitarian aid entering the enclave has dropped by two-thirds since Israel began its military operation in the enclave's southern Rafah region this month.

"The amount of food and other aid entering Gaza, already insufficient to meet the soaring needs, has further shrunk since 7 May," the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) said.

A daily average of 58 aid trucks reached Gaza from May 7 to Tuesday, compared with a daily average of 176 aid trucks from April 1 to May 6, OCHA said, a drop of 67%. It said those figures excluded private sector cargo and fuel.

The United Nations has long said at least 500 trucks a day of aid and commercial goods need to enter Gaza.

Since the Israel-Hamas war began nearly eight months ago, aid for 2.3 million Palestinians has primarily entered through two crossings into southern Gaza - the Rafah crossing from Egypt and the Kerem Shalom crossing from Israel.

But deliveries were disrupted when Israel stepped up its military operations in Rafah with the stated aim of routing remaining units of Hamas fighters. Egypt closed the Rafah crossing due to the threat posed to humanitarian work but on Friday agreed to temporarily send a backlog of aid and fuel via Kerem Shalom.

Aid shipments have diminished "due to the closure of Rafah crossing, the inability to safely and consistently pick up commodities from the Kerem Shalom crossing and limited deliveries through other entry points," OCHA said.

Israel's Deputy U.N. Ambassador Jonathan Miller told the U.N. Security Council on Wednesday that Israel was fighting a war against Hamas, not the civilians of Gaza.

"This is why Israel is committed to facilitating the entry of humanitarian aid into Gaza from every possible point of entry. Despite Hamas rocket fire on the Kerem Shalom crossing, it is fully functional and aid trucks are entering," he said.

Aid deliveries by ship from Cyprus to a U.S.-built floating pier in Gaza began on May 17. But the U.S. said on Tuesday that the pier is being temporarily removed after a part broke off.

OCHA said that no aid had entered Gaza from the pier on Monday or Tuesday. While operational, the United Nations transported 137 trucks of aid from the pier, the equivalent of 900 metric tons, a U.N. World Food Programme spokesperson said.