The US has blocked the appointment of former Palestinian prime minister Salam Fayyad as UN envoy to Libya.
In a statement, American ambassador to the UN, Niki Haley, said the US did not "support the signal this appointment would send within the United Nations".
She further said: "For too long the UN has been unfairly biased in favour of the Palestinian Authority to the detriment of our allies in Israel. Going forward the United States will act, not just talk, in support of our allies."
UN Secretary General Antonio Guterres sent a letter to the Security Council indicating his intention to appoint Fayyad as the next representative to Libya and had given the council until Friday (10 February) to consider the choice.
Fayyad had previously served as the Palestinian Authority's prime minister from 2007 to 2013 and twice as its finance minister.
The Associated Press quoted UN diplomats as saying that Fayyad is a well respected figure for his work to reform the Palestinian Authority and spurring the economy and was supported by 14 other Security Council members for the new job.
Guterres' office said in a statement: "United Nations staff serve strictly in their personal capacity. They do not represent any government or country."
Danny Dannon, Israel's ambassador to the UN, hailed the decision to block Fayyad's appointment. It is not yet clear if the US objection to Fayyad's appointment has ended his candidacy.
Susan E Rice, former US ambassador to the UN from 2009 to 2013, tweeted condemning Haley's statement as "ignorant, offensive, counterproductive".