With a round of applause, the 189-member General Assembly approved a recommendation by the 15-member Security Council to appoint Annan for another five-year term.
Annan's election six months before his first term expires on Dec. 31 was in stark contrast with the last contest in 1996, when the United States blocked his predecessor, Boutros Boutros-Ghali of Egypt, from serving another five years. In Washington, Boutros-Ghali was perceived as anti-American.
In this case, President Bush was one of the first leaders to endorse Annan's candidacy, and on Friday acting U.S. Ambassador James Cunningham called him "a global citizen who gives voice to all the people of the United Nations."
With support from the United States and the other four veto-wielding members of the Security Council Russia, China, Britain and France his re-election was assured.
But Friday's General Assembly meeting provided the official seal of approval and gave representatives from every region the opportunity to add their support and their to-do lists for his next term.
Almost every speaker pointed to the agenda Annan drafted to reduce poverty, improve education, halt the AIDS pandemic and improve human rights in the 21st century. The plan was adopted at last September's Millennium Summit by over 150 world leaders, the largest-ever gathering of heads of state and government.
Traditionally, the United Nations' top job rotates every 10 years by region, and Africa should in theory be handing over the spacious office on the 38th floor of the U.N. Secretariat building to Asia on Jan. 1. But the re-election of the 63-year-old Ghanaian will give Africa an unprecedented 15 years at the helm of the world body.
General Assembly members applauded rather than voted when assembly President Harri Holkeri asked for their support after Security Council president Anwarul Chowdhury of Bangladesh read the resolution recommending Annan's appointment.
"His excellency, Mr. Kofi Annan, has been appointed by acclamation secretary general of the United Nations for a second term of office," Holkeri announced.
The Assembly president then invited Annan to the podium and as he entered the spacious wood-paneled chamber, diplomats from around the world rose and applauded.
"I am sustained by a profound feeling of gratitude for the confidence you have placed in me and for the encouragement and support I have received from so many quarters," Annan told the delegates. "I labor under a constant sensof obligation to you, the member states of the organization, to all the world's people, whom you represent, and in particular to my fellow Africans."
"Let me add the hope, Mr. President, that five years from now the peoples of the world whom this organization was founded to serve will feel that it is closer to them, working better to fulfill their needs and putting their individual welfare at the center of everything it does."
When Annan became the seventh U.N. secretary-general on Jan. 1, 1997, the first U.N. chief to come from its own ranks, the world body was under attack on many fronts and at odds with the United States.
The United Nations had failed to prevent or stop the 1994 genocide in Rwanda and the July 1995 Serb slaughter of Muslims in the U.N.-declared "safe zone" of Srebrenica in eastern Bosnia.
The legacy of the failed U.N. peacekeeping mission on Somalia also lingered, particularly in the United States, which lost 18 soldiers in a botched U.S. raid in the capital Mogadishu in 1993.
But nearly five years later, the United Nations is playing major peacekeeping roles on several continents with missions in Ethiopia-Eritrea, East Timor and Kosovo. Elsewhere in Africa, U.N. peacekeepers are trying to help the government of Sierra Leone enforce a cease-fire, and to end the continent's largest war in Congo.
Chowdhury said Annan "has excelled in his office, delivering under trying circumstances."
"His reform efforts of the United Nations have made the organization ready for the challenges of the 21st century," Chowdhury said. "He made the United Nations peacekeeping more relevant, more respectable in enhancing its effectiveness in bringing peace to suffering millions."
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