GENEVA, Aug. 18 (Xinhua) -- Former Secretary-General of the United Nations (UN) and Nobel Peace Prize laureate Kofi Annan passed away in Switzerland at the age of 80 on Saturday.

Annan died in hospital in Bern, Switzerland in the early hours of Saturday, and his wife Nane and their children Ama, Kojo and Nina were by his side during his last days, according to his associates and the Kofi Annan Foundation.

Born on April 8, 1938 in Kumasi, a commercial city in Ghana, Annan served as the seventh UN secretary-general from January 1997 to December 2006. He and the UN were the co-recipients of the 2001 Nobel Peace Prize.

He began studying economics at the Kumasi College of Science and Technology, now the Kwame Nkrumanh University of Science and Technology of Ghana, and completed his undergraduate studies in economics at Macalester College in St. Paul, the U.S. state of Minnesota in 1961.

After his graduation on international relations from a Swiss institute in Geneva in 1962 and years of work experience, he further studied at the MIT and earned a master's degree in management.

Fluent in English, French, Akan and some other African languages, Annan started working as a budget officer for the World Health Organization in 1962.

He has served several different UN positions since 1980, including the head of UN High Commission for Refugees and the under-secretary-general for peacekeeping between 1992 and 1996.

Annan was appointed as the UN secretary-general on Dec. 13, 1996 by the Security Council, and later confirmed by the General Assembly, making him the first office holder to be elected from the UN staff itself. He was re-elected for a second term in 2001.

As the UN chief, Annan reformed the UN bureaucracy; worked to combat HIV, especially in Africa; and launched the UN Global Compact.

After leaving the UN, he founded the Kofi Annan Foundation in 2007 to work on international development. He was also the chairman of The Elders, an international organization founded by Nelson Mandela.

Annan published his memoir, "Interventions: A Life in War and Peace," in 2012, sharing in the book his unique experiences during the Sept. 11 terrorist attacks, the American-led invasions of Iraq and Afghanistan, the conflict in the Middle East, the conflicts of Somalia, Rwanda, and Bosnia, as well as the geopolitical transformations following the end of the Cold War.

In the memoir, he joked that SG, the abbreviation for his title as UN secretary-general, carried a second meaning, that is, scapegoat.

Incumbent UN Secretary-General Antonio Guterres on Saturday voiced deep sorrow at the news that his predecessor Annan had passed away.

"Kofi Annan was a guiding force for good," Guterres said in a statement. "In many ways, Kofi Annan was the United Nations. He rose through the ranks to lead the organization into the new millennium with matchless dignity and determination."

"Like so many, I was proud to call Kofi Annan a good friend and mentor," he said in the statement.