By Michelle Nichols

UNITED NATIONS (Reuters) -The United Nations said on Monday that it has only been able to bring minimal flour into Gaza since Israel lifted an aid blockade three weeks ago and that has mostly been looted by armed gangs or taken by starving Palestinians.

The organization has transported 4,600 metric tonnes of wheat flour into Gaza via the Kerem Shalom crossing, the only entry point Israel allows it to use, Deputy U.N. spokesperson Fahan Haq told reporters.

Haq said aid groups in Gaza estimate that between 8,000 and 10,000 metric tonnes of wheat flour were needed to give each family in Gaza a bag of flour and "ease the pressure on markets and reduce desperation."

"Most of it was taken by desperate, starving people before the supplies reached their destinations. In some cases, the supplies were looted by armed gangs," Haq said.

According to World Food Programme guidelines, 4,600 metric tonnes of flour would provide roughly eight days’ worth of bread for Gaza’s 2 million residents, based on a standard daily ration of 300 grams per person.

Haq called for Israel to let in far more aid via multiple crossings and routes.

The U.N. has mostly delivered flour along with limited medical and nutrition items since Israel lifted the 11-week blockade in mid-May. Experts warn Gaza is at risk of famine, with the rate of young children suffering acute malnutrition nearly tripling.

Israel and the United States want the U.N. to work through the controversial new Gaza Humanitarian Foundation, but the U.N. has refused, questioning its neutrality and accusing the distribution model of militarizing aid and forcing displacement.

Israel and the United States have accused Hamas of stealing aid from the U.N.-led operations, which the militants deny.

The GHF uses private U.S. security and logistics firms to operate. It began operations in Gaza on May 26 and said on Monday so far it has given out 11.4 million meals.

Israel makes the U.N. offload aid on the Palestinian side of the Kerem Shalom crossing, where it then has to be picked by the U.N. and aid groups already in Gaza. The U.N. has accused Israel of regularly denying access requests.

(Reporting by Michelle Nichols; Editing by Cynthia Osterman)