Michelle Bachelet of Chile, Rebeca Grynspan of Costa Rica and Maria Fernanda Espinosa of Ecuador are all standing to succeed Antonio Guterres, who is stepping down at the end of the year after two five-year terms.The trio touted their diplomatic credentials during a debate organised by independent organisations in Geneva, the city home to the UN's European headquarters."I think, of course, a woman -- it's about time, isn't it? After 80 years" of the UN's existence, said Espinosa, a former foreign minister.But the next secretary-general should be "the best woman, not any woman", the 61-year-old added; a "leader with a lot of energy".Many countries are advocating for a woman to head the UN for the first time, and Latin America is claiming the position based on a tradition of geographical rotation -- which is not always strictly followed."Women can bring more humanism," said the Chilean ex-president Bachelet, who is also a former UN rights chief.

Maria Fernanda Espinosa was the foreign minister of Ecuador from 2017 to 2018 © Fabrice COFFRINI / AFP

She likewise said the next chief should be a woman, "but not any woman", saying she was someone unafraid of "risking that what I try doesn't work"."I'm not afraid of speaking up when it's needed," she added.Meanwhile Grynspan, 70, the head of the UN trade and development agency UNCTAD, said she was running "because I think I am the best person for the job".The former vice president of Costa Rica is calling for a selection process free from any preferential treatment for women.The debate was held at the Maison de la Paix, which houses several organisations and is a stone's throw from the UN Palais des Nations.Also invited were the two other declared candidates: Argentina's Rafael Grossi, the head of the International Atomic Energy Agency; and the former president of Senegal, Macky Sall, with the latter sending a short video message.UN 'irreplaceable'The UN General Assembly of member states can only elect the secretary-general after a recommendation from the UN Security Council, where the five permanent members -- Britain, China, France, Russia and the United States -- wield veto power.