UNITED NATIONS -- UN Secretary-General-designate Antonio Guterres was sworn in as the new secretary-general of the world body at an oath of office ceremony here on Monday.

UN Secretary-General designate Antonio Guterres (R) stands with UN Secretary-General Ban Ki-moon (L) after being sworn in as the new Secretary-General of the United Nations during a ceremony in the General Assembly hall at United Nations headquarters in New York, New York, USA, 12 December 2016. Guterres will officially take over the position from Ban Ki-moon on 01 January 2017.?[Photo/IC]

Witnessed by senior diplomats of member states and senior UN officials, Guterres repeated the oath after current General Assembly President Peter Thomson.

"I, Antonio Guterres, solemnly swear to exercise in all loyalty, discretion and conscience the functions entrusted to me as Secretary-General of the United Nations, to discharge these functions and regulate my conduct with the interests of the United Nations only in view, and not to seek or accept instructions in regard to the performance of my duties from any government or other authority external to the organization."

On Oct. 13, the UN General Assembly appointed former Prime Minister of Portugal Antonio Guterres as the 9th secretary-general of the United Nations to succeed retiring Ban Ki-moon who steps down at the end of this year.

The five-year term for Guterres will start on Jan. 1, 2017 and end on Dec.31, 2021.

Guterres, a 67-year-old politician, served as UN High Commissioner for Refugees from June 2005 to December 2015. Before joining the UN refugee agency, Guterres spent more than 20 years in government and public service. He was the prime minister of Portugal from 1995 to 2002.