WASHINGTON - All 100 U.S. Senators signed a letter on Thursday calling on UN Secretary-General Antonio Guterres to take action against the organization's "anti-Israel agenda."

The letter stated that "although as Republicans and Democrats we disagree on many things, we are united in our desire to see the United Nations improve its treatment of Israel."

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The letter, which was first published by The Washington Post, also included praise for Guterres, who recently denounced an anti-Israeli report prepared by a UN agency called the United Nations Economic and Social Commission for Western Asia (ESCWA) that is used primarily as a platform for attacking Israel. Guterres has also stated that denying Israel's right to exist is a "modern form of anti-Semitism."

The Senators, however, also asked the UN chief to take concrete steps to improve the organization's treatment of Israel. Among those steps: reforming or eliminating committees that "serve no purpose than to attack Israel"; changing the way in which UNESCO, the UN's agency for education, culture and science, addresses Israel and the Jewish connection to Jerusalem; reforming UNRWA, the UN agency in charge of Palestinian refugees across the Middle East, which the Senators say "downplays its role in perpetuating troubling anti-Israel bias and activities"; and ending the UN Human Rights Council's "unfair and unbalanced" focus on Israel.

The Senators note that "as both the UN's principal founding member, and its largest contributor, the United States should insist on reform. As duly elected representatives of the American people, we take seriously our responsibility to conduct rigorous oversight of U.S. engagement in the United Nations."

Last week, U.S. Ambassador to the United Nations Nikki Haley told the 15-member Security Council that its monthly meetings on the Middle East - traditionally focused on Israel and the Palestinians, Syria and Lebanon - regularly turned into "Israel-bashing sessions."

"Iran is using Hezbollah to advance its regional aspirations. They are working together to expand extremist ideologies in the Middle East," she said. "That is a threat that should be dominating our discussion at the Security Council."