The former United Nations Secretary General died in a hospital in Switzerland in the early hours of Saturday morning.
According to the Kofi Annan Foundation he passed away peacefully after a short illness. His wife and children were by his side. According to the Reuters news agency, the 80-year-old was admitted to a hospital in the Swiss capital of Bern where he died.
The international diplomat had strong ties to Switzerland, in particular Geneva. He called Geneva his second home. Annan studied at the Graduate Institute of International Studies from 1961-62 and where he began his UN career at the World Health Organization. It was also where he met his wife, Nane, a Swedish lawyer.
The Ghanian national lived in Geneva from 2006 after the end of his second term as the UN chief. A year later he established the Kofi Annan Foundation in the Swiss city.
Swiss president Alain Berset expressed his condolences to Annan's family via Twitter and called him a visionary and a great friend of Switzerland.
"Today, International Geneva has lost one of its most ardent advocates," he added.
Pierre Maudet, president of the Geneva cantonal government, said he was "sad" to learn about Annan's death whom he considered "a great friend of Geneva and Switzerland". He expressed a wish for Geneva to pay homage to Annan but said it was necessary to discuss the subject with the family first.
The director-general of the UN European headquarters in Geneva, Michael Møller, said he was shocked by how rapidly Annan's condition deteriorated. He termed Annan's death an "enormous loss for the world".