The United States blocked the appointment of former Palestinian prime minister Salam Fayyad to be the new UN envoy to Libya, diplomats said.
UN Secretary-General Antonio Guterres had informed the Security Council this week of his intention to name Fayyad to lead the UN support mission in Libya and help broker talks on a faltering political deal.
The UN chief gave the council until on Thursday to consider the choice and the United States came forward to raise objections.
The US mission did not immediately respond to a request for comment.
Fayyad, 65, was prime minister of the Palestinian Authority from 2007 to 2013 and also served as finance minister twice.
He had been tapped to replace Martin Kobler of Germany, who has been the Libya envoy since November 2015.
It was the first major appointment by Guterres of a special envoy to a conflict area since he became UN chief on January 1.
US President Donald Trump and Ambassador Nikki Haley have criticized the United Nations for adopting a resolution in December that demanded an end to Israeli settlement building.
Haley has vowed to defend Israel’s interests at the world body.