South Korea's foreign minister is now a formal candidate to become the next United Nations secretary-general. Ban Ki-moon is a seasoned diplomat with experience in sensitive North Korean nuclear negotiations.

Ending months of public speculation, South Korean Vice Foreign Minister Yu Myung-hwan confirmed Tuesday that Foreign Minister Ban Ki-moon hopes to replace Kofi Annan as United Nations secretary-general.

Yu says Seoul will send a letter to notify the U.N. Security Council formally of Ban's candidacy later this year.

Annan is due to step down on December 31, after serving two five-year terms.

Before becoming foreign minister in 2004, Ban served as national security advisor as well as South Korea's ambassador to the United Nations. He says he will conduct a quiet campaign to become secretary-general.

Ban says he will work mainly through South Korea's international organizations to build support around the world.

Ban is one of Seoul's key players in negotiations to end North Korea's nuclear weapons programs. China, Russia, the United States, Japan, and South Korea have tried for three years to convince Pyongyang to live up to previous commitments to remain free of nuclear weapons.

Limb Thok-kyu, a former South Korean lawmaker and now chairman of Diplomacy magazine, says Ban's role in the nuclear talks has helped him form important relationships.

Limb says Ban has formed close friendships with his counterparts in the United States, China, and Russia - which may translate into support for his candidacy.

Those countries make up three of the five permanent members of the U.N. Security Council. Experts say it is crucial for any secretary-general candidate to be acceptable to all five permanent members, since they have veto authority.

Some aspects of South Korean policy have generated controversy internationally. The administration of President Roh Moo-hyun, which supports cooperation and engagement with North Korea, has abstained from three widely supported U.N. votes criticizing Pyongyang's human rights record.

By U.N. tradition, the post of secretary-general has rotated to different regions of the world. An Asian has not held the job since Burma's U Thant retired in 1971, and many in the diplomatic community to suggest it is once again Asia's turn. Sri Lanka and Thailand have named their own candidates for the position.

The new secretary-general will be selected late this year.