United Nations - Ban Ki-moon, the South Korean foreign minister, moved significantly closer on Thursday to becoming the successor to Kofi Annan as United Nations secretary general by maintaining a wide lead over six other candidates in the Security Council's third informal poll.

A fourth and more definitive informal poll is scheduled for Monday, and Ban, with 13 favorable votes from the 15 Council members, goes into that poll as the only candidate with the nine votes required for approval.

On Monday, the ballots of the five permanent members, Britain, China, France, Russia and the United States, will be colored different than the others, a way of determining whether any nation with veto power has exercised it. Barring a veto, Mr. Ban's election in a subsequent formal vote appears assured.

Associated Press reported that Ban was followed by  Shashi Tharoor of India, 50, the under secretary general for public information, who saw his support diminish to 8 favorable votes from 10. Vaira Vike-Freiberga, 68, the president of Latvia, a new entry and the only woman under consideration came the third with seven favorable votes.

The other new candidate, Ashraf Ghani, 57, a former finance minister of Afghanistan and the current chancellor of Kabul University, managed to attract only three.

Surakiart, 47, deputy prime minister of Thailand, saw his positives fall to five from nine. Both Prince Zeid Raad Zeid al-Hussein, 42, Jordan's ambassador to the United Nations, and Jayantha Dhanapala, 67, of Sri Lanka, a former under secretary general for disarmament, drew only three positive votes.

So far there was no indication that anyone would drop out of the race.

Thailand's U.N. ambassador, Laxanachantorn Laohaphan, said Surakiart would not withdraw, and Ghani said in an interview that his campaign would continue.

Ban has a master's degree from the Kennedy School of Government at Harvard, was assigned twice to the South Korean Embassy in Washington and is a former director general of American affairs for South Korea's Foreign Ministry.

He has the firm backing of the Bush administration and is known as an ally of Washington. If he gets the job, that part of his political makeup will be closely monitored at the United Nations, where tensions between the United States and the developing world have been on the rise.

Mr. Annan steps down December 31 after two five-year terms. Under United Nations procedures for choosing a secretary general, the Security Council selects one name and sends it to the 192-member General Assembly for ratification.

Six of the seven candidates are Asian, in keeping with the unwritten but accepted notion at the United Nations that this year it is Asia's turn to occupy the top job. The last Asian secretary general was U Thant of Burma, who left office in 1971.

Associated Press