Distributions will halt on Thursday, said United Nations Relief and Works Agency for Palestinian Refugees (UNRWA) Commissioner-General Peter Hansen on Tuesday.
Between 700,000 and 1.2 million Palestinians will be affected by the move, he said.
The distributions are "very important because the food situation in Gaza has been getting progressively worse," he told Aljazeera.net, adding Palestinians in the occupied West Bank will also be affected.
Hansen said it is unclear how long the population will be able to survive without the UN’s aid packages but stressed the current situation is serious and will only deteriorate if distribution does not resume soon. While there is no danger of starvation, there will be severe malnutrition and hunger, said the UN aid chief.
Israel is refusing to allow empty containers used by the aid agency to leave the Gaza Strip. The blockage is causing "intolerable costs to a programme which is already stung by under-funding," said Hansen.
Israeli authorities say they have imposed the block for security reasons, fearful that Palestinian activists will be smuggled out in the containers, says Hansen.
"It would be very difficult to hide inside an empty container unless you have ghost-like qualities"
"I fail to see that it is difficult to look into an empty container and see that there are no persons trying to infiltrate into any place," he said. "It would be very difficult to hide inside an empty container unless you have ghost-like qualities," he added.
UNRWA began distributing food in the occupied West Bank and Gaza Strip at the beginning of the Intifada in 2001 when the economic situation deteriorated due to blanket Israeli closures.
Hansen said the UN body has repeatedly contacted every conceivable Israeli authority to discuss the closure.
"I was amazed to see that the Israeli ambassador in New York was complaining that we were going to the press before going to the Israelis. This is simply completely incorrect," he said.
In March, the UN body sent 12 letters, made dozens of phone calls and held several meetings with Israeli authorities to discuss the blockage in Gaza, said Hansen. He wrote to the Israeli defence minister and foreign minister. He is still waiting for a response.
"We have complained loudly and clearly and the notion that this is only brought out publicly without complaining is simply ludicrous," he said.
Staff in danger
It has also become increasingly dangerous for UN staff to enter and leave Gaza, forcing Hansen to instruct UNRWA workers not to enter the area on foot. Until a few weeks ago, international staff had permission from Israeli occupation forces to enter and leave the area by vehicle. This privilege has been lifted.
Members of UNRWA were using a tunnel which Israeli soldiers force Palestinian workers to use, dubbed the "cattle chute", said Hansen.
Hansen hopes the suspension of food distribution will be temporary and the Israelis "live up to their obligations of assisting us in our operations rather than hindering us".
"I see a humanitarian crisis that has lasted already for some years and will only get worse if we don’t get agreements and arrangements in this field."