Tributes have been pouring in from world leaders and diplomats.
Current UN chief Antonio Guterres has been leading the tributes to his predecessor, describing Mr Annan as “a guiding force for good”.
“In many ways, Kofi Annan was the United Nations. He rose through the ranks to lead the organisation into the new millennium with matchless dignity and determination,” he said in a statement.
UN high commissioner for human rights Zeid Raad Al Hussein said in a tweet he was grief-stricken over Annan’s death:
Sad to hear of the death of Kofi Annan. A great leader and reformer of the UN, he made a huge contribution to making the world he has left a better place than the one he was born into. My thoughts and condolences are with his family.
I am grief-stricken over the death of Kofi Annan. Kofi was the epitome of human decency and grace. In a world now filled with leaders who are anything but that, the world’s loss becomes even more painful. He was a friend to thousands and a leader of millions.
— Zeid Raad Al Hussein (@raad_zeid) August 18, 2018
Sad to hear of the death of Kofi Annan. A great leader and reformer of the UN, he made a huge contribution to making the world he has left a better place than the one he was born into. My thoughts and condolences are with his family. pic.twitter.com/P0SWagShJM
— Theresa May (@theresa_may) August 18, 2018
Deeply saddened by the passing away of Kofi Annan. One of the true global leaders of our age. A man of courage, wisdom and friendship. I’m honored to have had the privilege of working for him. pic.twitter.com/a9pTv0cdF1
— Carl Bildt (@carlbildt) August 18, 2018
Saddened to hear that Kofi Annan has passed away. His warmth should never be mistaken for weakness. Annan showed that one can be a great humanitarian and a strong leader at the same time. The UN and the world have lost one of their giants.
— Jens Stoltenberg (@jensstoltenberg) August 18, 2018
Kofi Annan, the first black African to become UN secretary-general, died aged 80 in Switzerland.
He “passed away peacefully on Saturday after a short illness”, the Kofi Annan foundation announced on Saturday.
In a statement announcing his death, the Kofi Annan Foundation described him as a “global statesman and deeply committed internationalist who fought throughout his life for a fairer and more peaceful world”.
“Wherever there was suffering or need, he reached out and touched many people with his deep compassion and empathy. He selflessly placed others first, radiating genuine kindness, warmth and brilliance in all he did.”
Mr. Annan served two terms as UN chief from 1997 to 2006, and was awarded a Nobel Peace Prize for humanitarian work for his efforts.
He later served as the UN special envoy for Syria, leading efforts to find a peaceful solution to the conflict.
Annan’s diplomatic career continued after retirement from the UN, with a successful role in negotiations for a power-sharing deal to end post-election violence in Kenya in 2008. A year earlier, he set up his foundation aimed at promoting global sustainable development, security and peace.
In 2012 he was made chair of The Elders, a peace and human rights advocacy group started by South Africa’s Nelson Mandela.
His most recent role was chairing an independent commission investigation Myanmar’s Rohingya crisis.
Annan’s wife, Nane, and three children were “by his side during his last days”, the Kofi Annan Foundation said.
Ghana’s President Nana Addo Dankwa Akufo-Addo has ordered flags be flown at half-mast across the country and in diplomatic missions across the world for seven days, starting on Monday.