One is accused of kidnapping a woman. Another is said to have handed out ammunition. A third was described as taking part in the massacre at a kibbutz where 97 people died. And all were said to be employees of the United Nations aid agency that schools, shelters and feeds hundreds of thousands of Palestinians in the Gaza Strip.

The accusations are contained in a dossier provided to the United States government that details Israel’s claims against a dozen employees of the United Nations Relief and Works Agency who, it says, played a role in the Hamas attacks against Israel on Oct. 7 or in their aftermath.

The U.N. said on Friday that it had fired several employees after being briefed on the allegations. But little was known about the accusations until the dossier was reviewed on Sunday by The New York Times.

The accusations are what prompted eight countries, including the United States, to suspend some aid payment to UNRWA, as the agency is known, even as war plunges Palestinians in Gaza into desperate straits. More than 26,000 people have been killed there and nearly two million displaced, according to Gazan and U.N. officials.

The UNRWA workers have been accused of helping Hamas stage the attack that set off the war in Gaza, or of aiding it in the days after. Some 1,200 people in Israel were killed that day, Israeli officials say, and about 240 were abducted and taken to Gaza.

On Sunday, the United Nations secretary general, António Guterres, described himself as “horrified by these accusations” and noted that nine of the 12 accused employees had been fired. But Mr. Guterres implored those nations that had suspended their aid payments to reconsider. UNRWA is one of the largest employers in Gaza, with 13,000 people, mostly Palestinians, on staff.