UN Secretary-General Antonio Guterres has expressed his "deep appreciation for the excellent cooperation and support" of US Ambassador Nikki Haley, who earlier handed in her resignation at the White House.
The spokesman said the Secretary-General, en route to Indonesia, had not received notice of her resignation and didn't expect to receive it until closer to when she plans to step down, at the end of the year, probably about the time her successor is announced.
Guterres plans to meet in Bali, Indonesia with leaders of the Association of South-East Asian Nations at their Leaders Gathering, then with officials of the International Monetary Fund and the World Bank Group at their annual meeting.
On Friday he is expected to visit Palu, Sulawesi, the spokesman said.
(With inputs from agencies.)