The United Arab Emirates arranged the trip to Rafah - where limited humanitarian aid and fuel deliveries have crossed into Gaza - as the 15-member council negotiates a UAE-drafted resolution that demands the warring parties "allow the use of all land, sea and air routes to and throughout" Gaza for aid.

It would also establish a U.N.-run aid monitoring mechanism in Gaza Strip. It was not immediately clear when the draft resolution could be put to a vote.

UAE U.N. Ambassador Lana Nusseibeh said the aim of the visit was "to learn first-hand what is needed in terms of a humanitarian operations scale-up that meet the needs of the Palestinian people in Gaza." She noted it was not an official Security Council visit.

The United States is not sending a representative on the trip, which follows a U.S. veto last week of a proposed U.N. Security Council demand for an immediate humanitarian ceasefire in the war between Israel and Palestinian militant group Hamas in Gaza.

"The United States is keenly aware of the very difficult situation at Rafah and is working around the clock to try to improve the situation on the ground," said Nate Evans, spokesperson for the U.S. Mission to the United Nations.

He said U.S. diplomacy "continues to produce results" and that Washington has been "clear that more assistance is needed and continue to support humanitarian pauses during which hostages can be released and aid can be surged."

France and Gabon are also not sending representatives on the trip to Rafah. The French U.N. mission did not immediately respond to a request for comment.

"I urged the Security Council to press to avert a humanitarian catastrophe in Gaza and I reiterated my appeal for a humanitarian ceasefire. Regrettably, the Security Council failed to do it," Guterres posted on social media on Sunday.

"But that does not make it less necessary. I promise: I will not give up," wrote Guterres, who made the rare move to formally warn the Security Council on Wednesday of the global threat to peace and security posed by the conflict.

GENERAL ASSEMBLY VOTE

The U.N. General Assembly will meet on Gaza on Tuesday at the request of Arab and Organization for Islamic Cooperation (OIC) states. The 193-member body is likely to vote on a draft resolution demanding an immediate humanitarian ceasefire, diplomats said.

In October the assembly adopted a resolution - 121 votes in favor, 14 against and 44 abstentions - calling for "an immediate, durable and sustained humanitarian truce leading to a cessation of hostilities."

Israel has bombarded Gaza from the air, imposed a siege and launched a ground offensive in retaliation for an Oct. 7 attack by Hamas that Israel says killed 1,200 people and saw 240 people taken hostage. Gaza health authorities say around 18,000 people have been killed by Israeli attacks, with 49,500 injured.

The vast majority of the Palestinian enclave's 2.3 million people have been driven from their homes. Guterres told the Security Council on Friday: "Half the people of the north and more than one third of displaced people in the south are simply starving."

The U.N. Office for the Coordination of Humanitarian Affairs said that 100 trucks carrying humanitarian supplies entered Gaza from Egypt on Sunday, the same number as the previous day.

It noted that was "well below" the daily average of 500 truckloads, including fuel, that entered every working day prior to Oct. 7.

"The conditions for the effective delivery of humanitarian aid no longer exist," Guterres said on Friday. "The crossing point at Rafah was not designed for hundreds of trucks and is a major bottleneck."

The U.N. has been pushing for the opening of the Kerem Shalom crossing, controlled by Israel. Israel has agreed to allow it to be used for inspections, but not to enter Gaza. Trucks would be inspected there before entering Gaza from Rafah, about 3km (2 miles) away.

The UAE also invited incoming Security Council members Algeria, Guyana, Sierra Leone, Slovenia and South Korea, who start their two-year terms on Jan. 1, replacing Albania, Brazil, Gabon, Ghana and the UAE. Only Algeria did not send an envoy.

(Writing and additional reporting by Michelle Nichols; Editing by Don Durfee and Lincoln Feast.)

By Alexander Cornwell