Antonio Guterres, Portugal's ex-prime minister who was UN refugee chief for 10 years, led the closely watched first straw poll vote Thursday to pick the next UN secretary-general, diplomats said. Slovenia's former president Danilo Turk came second in the secret vote by the UN Security Council to choose a successor to Ban Ki-moon. The 15 ambassadors including those from the powerful five -- Britain, China, France, Russia and the United States -- each rated the candidates with ballots marked "encourage," "discourage" or "no opinion." Guterres won the top score of 12 "encourage" votes with three "no opinion." Turk was close behind with 11 encouragements, two "discourage" votes and three "no opinion," according to diplomats. Portugal's Foreign Minister Augusto Santo Silva described the result as "extremely positive" and said it confirmed that Guterres is "particularly qualified for the position of secretary-general." UNESCO chief Irina Bokova of Bulgaria received nine encouragements as did Serbia's ex-foreign minister Vuk Jeremic and Srgjan Kerim, Macedonia's former foreign minister. New Zealand's Helen Clark, a former prime minister who heads the UN Development Programme, picked up eight encouragements but in a potential blow to her campaign, received five "discourage" votes. There are currently 12 candidates in the race, six of them women, but diplomats expect some to withdraw based on the result of the first round. Argentina's Foreign Minister Susana Malcorra, who served as Ban's chief of staff, failed to make a strong showing, receiving fewer encouragements than Clark as did Slovakia's Foreign Minister Miroslav Lajcak. Croatia's former foreign minister Vesna Pusic received 11 discouragements from the council, the lowest score. Moldova's Natalia Gherman, Montenegro's Igor Luksic and former UN climate chief Christiana Figueres of Costa Rica were among the bottom tier. Council members are expected to meet again, possibly as early as next week, for a second round of straw polls, with a final nominee expected to emerge by October. - The man to beat - The secret vote followed a new, more open process that for the first time in UN history provided for hearings to allow candidates to present their pitch for the top job before the General Assembly. Fluent in Portuguese, English, Spanish and French, the 67-year-old Guterres impressed UN diplomats when he appeared at the hearings and he has earned praise for his handling of Europe's refugee crisis as high commissioner. A trained engineer, Guterres led the refugee agency until December last year and served as Portugal's socialist prime minister from 1995 to 2002. "Guterres is the man to beat," a Security Council diplomat told AFP. "He has done very well." Slovenia's president from 2007 to 2012, 64-year-old Turk also served as the country's first UN ambassador and as UN assistant secretary-general for political affairs from 2000 to 2005. Turk tweeted that he was "grateful for attention, understanding and encouragement of the UN member states and civil society", adding that he now had a "great platform for the next rounds." Council members are facing calls to pick the first female secretary-general after eight men in the job, and to give preference to a candidate from eastern Europe, the only region that has yet to be represented in the top post. British Ambassador Matthew Rycroft said "it is high time for a woman" but added that there were "very, very strong men" in the race and that Britain would not use its veto to block a man from winning the post. For Britain, supporting a candidate from eastern Europe is "the least important criteria here," he said. US Ambassador Samantha Power said the United States would back a candidate with "great leadership and management skills" and who has a "commitment to fairness and accountability." French Ambassador Francois Delattre said the world's new number one diplomat must have "leadership, diplomatic skills and multilingualism." After agreeing on a nominee, the council will ask the General Assembly to endorse the choice. The new secretary-general will begin work on January 1.