The United States and Israel have sent complaint letters to top United Nations officials contesting the impartiality of their staff over the Israel-Hamas War, documents showed, as hundreds of UN staff protested outside its European headquarters on Thursday.

The letters highlight the rising tensions between the UN and its top funder, the US, which has already disengaged from the UN Human Rights Council over what Washington says is its anti-Israel stance.

UN staff carried placards saying "Peace for Gaza" and "Not a Target." They laid white roses next to a memorial plaque in Geneva to represent UN-associated workers killed in the nearly two-year war.

"Today, the UN staff are coming together to say that enough is enough, to say that we cannot kill our colleagues in Gaza with such impunity and to say stop to all these murders," Nathalie Meynet, president of the UN refugee agency staff council, told Reuters at the protest.

Israel's UN ambassador denounced the event

Israel's ambassador to the UN in Geneva, Daniel Meron, wrote ahead of the event to the Director-General of the United Nations' Geneva office, Tatiana Valovaya, denouncing the event.

Staff of the United Nations agencies gather to denounce their colleagues killed in Gaza since October 2023 outside the European headquarters in Geneva, Switzerland, September 18, 2025
Staff of the United Nations agencies gather to denounce their colleagues killed in Gaza since October 2023 outside the European headquarters in Geneva, Switzerland, September 18, 2025 (credit: REUTERS)

"UN staff are not activists or political actors...Those who incite and participate in such politically charged activities should face disciplinary measures, including suspension," his letter dated September 10 showed.

Séverine Deboos, one of the event's organizers, denied that its purpose was political: "The message is in honor of our colleagues (in Gaza) and to thank them," she said.

Israel takes extensive care to avoid civilian deaths in its war against Hamas.

'Grave violation of neutrality'

Several hundred people joined in the protest and a minute of silence outside the UN building.

Earlier this week, a thousand UN employees joined an online briefing with Francesca Albanese - a UN independent expert whose criticism of Israel has led to US sanctions.

Both Israel's Meron and US Charge d'Affaires Tressa Finerty complained to Valovaya about the call, with the latter saying in her September 16 email that the matter would also be raised with United Nations Secretary-General Antonio Guterres.

"This is a grave violation of the UN's principle of neutrality on multiple levels," said Finerty in an email.

"If UN staff during the UN workday, using UN email addresses and UN computers on UN-supplied smartphones, participate in this Teams meeting, there can be no dodging the charge that the UN is systematically and uniquely anti-Israel and, because of that, antisemitic."

A staff union member confirmed the Albanese meeting but said it involved core UN work.

The US diplomatic mission in Geneva declined to comment. A UN spokesperson did not immediately respond to request for comment.

UN staff losses in Gaza War

Under Standards of Conduct for the International Civil Service adopted by the UN, staff are advised not to take sides or express their convictions publicly on controversial matters.

UN staff representatives received a management note on September 17 asking them to stay impartial on the Gaza conflict, according to a confidential memo seen by Reuters.

Under-Secretary-General for Management Strategy, Policy and Compliance Catherine Pollard on September 17 acknowledged that the loss of colleagues had caused "immense suffering," adding: "I want to remind you that staff associations should not organize or promote activities that may be perceived as political in nature," the letter said, warning of risks for the organization.

Yousra Ahmed, a UN staff worker at the protest, said: "It's not a question of neutrality. I'm just outraged that the rules of the United Nations and humanitarian law are not being applied."