Though the results of the vote were not officially disclosed, Chinese ambassador Wang Guangya said Ban had received 14 votes in favour and one abstention in Monday evening's vote, which marked the first time the council's five permanent members - the US, Russia, Britain, France and China - could use their vetoes to shorten the field of six candidates.
'I think it is quite clear from today's straw poll that Ban Ki Moon is the candidate that the Security Council will recommend to the General Assembly,' Guangya said.
UN Undersecretary General Shashi Tharoor of India, who has come in second to Ban in all four informal votes, said he was stepping out of the race after Monday's poll and had offered Ban his 'warmest congratulations.'
'It is clear that he will be our next Secretary General,' Tharoor said, promising to offer Ban his full support.
Tharoor's departure leaves only five candidates - from Thailand, Latvia, Jordan and Afghanistan - aside from Ban. Sri Lanka's Jayantha Dhanapala had already withdrawn his name on Friday.
The Security Council is now likely to move to a formal vote some time next week, and will meet to set a date Tuesday. One formal vote is likely all that will be needed for the 15-nation council to recommend Ban for the UN's top job.
'We are coming pretty close to formal decision making,' Japanese Ambassador and Security Council President Kenzo Oshima said after Monday's vote.
A career diplomat, 62-year-old Ban has served as South Korea's ambassador to the United Nations and has also been a key player in six-nation talks on North Korea's nuclear programme. He officially threw his hat into the ring to become the next UN secretary general in February.
The UN General Assembly needs to approve the council's choice, but that is widely considered a formality.
Foreign Minister Ban's emergence follows a swirl of tense diplomacy and rumours among the nations vying for the UN post, even if the South Korean's front-runner status has never really appeared in doubt.
Thai daily The Nation reported last Thursday that the United States was poised to propose Thailand's former foreign minister Surin Pitsuwan for the job, citing an 'informed source,' though the article was met with skepticism by Surin himself.
Thailand already has a candidate for the UN post, former foreign minister Surakiart Sathirathai, who has come in third in previous polls and has the backing of the Association of South-East Asian Nations (ASEAN), and whose candidacy was endorsed by Thailand's ruling junta last week.
Greece's ambassador meanwhile was forced to reject charges Friday that commercial interests prompted it to support Ban, after South Korean President Roh Moo-hyun visited Athens in August at a time of heavy lobbying by the Seoul government.
Germany had spoken out in favour of Tharoor in the past, while the United States fancied 'outsider' Prince Zeid al-Hussein, the Jordanian permanent representative to the UN.
US Ambassador John Bolton refused to give the particulars of Monday's straw poll, but did say his country was satisfied with the result.
'I can say the US is very pleased with the outcome of the vote,' Bolton said. 'I urged that the council move as soon as possible to a formal vote.'
New candidates for the job can still come forward and have made late charges in the past, including Annan in December 1996. But Bolton said that was 'highly unlikely' this time.
According to the UN's unwritten rotational arrangement, the next secretary general should be an Asian. The last Asian to fill the post was Burmese national U Thant, who served between 1961 and 1971.
Annan's 10-year term as secretary general ends December 31.
