The race to be the next Secretary-General of the UN remains wide open as speculation mounts that the current front-runner for the job could be sidelined by a surprise last-minute entry to the contest.

Antonio Guterres, the former prime minister of Portugal and head of the UN refugee agency, has been the preferred candidate in every one of the four straw polls held since the contest began in April.

But, with the UN having stated that it is high time for a woman to lead the 70-year-old organisation, many expect Bulgarian diplomat Kristalina Georgieva to throw her hat in the ring.