Former Portuguese Prime Minister Antonio Guterres has been chosen to be the next Secretary General of the United Nations, following a unanimous decision by the organisation's Security Council.

Guterres, 66, who served as chief of the United Nations High Commission for Refugees for a decade, will take over from incumbent Ban Ki-moon in January. Ban served in the position for 10 years.

The decision was made in a straw poll held in New York on Wednesday (5 October), with a formal vote to take place on Thursday.

None of the 15 members of the council opposed Guterres' candidacy after the secret ballot.

The appointment will be put to the UN General Assembly for formal approval.

Guterres will take over over at a difficult time for the UN, amid the refugee crisis, conflicts in Syria, Yemen, and Libya, and increasing tension between Russia and the West.

Guterres' experience dealing with refugee issues is believed to have won him the support of Security Council members. Russian backing for Guterres' candidacy surprised some observers, who believed they were determined to back an eastern European candidate, while the US and UK had pushed for a female candidate to take the role.