U.N. diplomats say Portugal's former prime minister Antonio Guterres has maintained his spot as first choice to succeed Ban Ki-moon as U.N. secretary-general, topping the fourth successive informal poll in the Security Council.

The diplomats, speaking on condition of anonymity because voting is supposed to be kept secret, said Slovakia's Foreign Minister Miroslav Lajcak remained in second place followed by Serbia's former foreign minister Vuk Jeremic.

Former Macedonian foreign minister Srgjan Kerim moved up from sixth to fourth place and was followed by the only woman in the race, Argentina's Foreign Minister Susana Malcorra, the diplomats said.

Malcorra's ranking among the 10 candidates was a disappointment to many countries hoping for the first female secretary-general when Ban's second five-year term ends on Dec. 31.