In Geneva, the Kofi Annan Foundation announced his peaceful death with “immense sadness” after a short illness, saying he was surrounded in his last days by his second wife Nane and children Ama, Kojo and Nina.

Annan served two terms as U.N. Secretary-General in New York from 1997-2006 and retired in Geneva and later lived in a Swiss village in the nearby countryside.

“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,” U.N. Secretary-General Antonio Guterres, whom Annan had chosen to head the U.N. refugee agency, said in a statement.

As head of U.N. peacekeeping operations, Annan was criticized for the world body’s failure to halt the genocide in Rwanda in the 1990s.

As U.N. boss he was linked to peace efforts to reunite the divided island of Cyprus. He submitted a reunification blueprint for Cyprus which was rejected in a referendum by Greek Cypriots in 2004.

“The U.N. can be improved, it is not perfect but if it didn’t exist you would have to create it,” he told the BBC’s Hard Talk during an interview for his 80th birthday last April, recorded at the Geneva Graduate Institute where he had studied.

“I am a stubborn optimist, I was born an optimist and will remain an optimist,” Annan added. 

U.N. High Commissioner for Human Rights, Zeid Ra’ad al-Hussein, paid tribute to Annan as “humanity’s best example, the epitome, of human decency and grace”.

Zeid, who has criticized major powers and other countries during his four-year term that ends later this month, said that whenever he felt “isolated and alone politically”, he would go for long walks with Annan in Geneva.

“When I told him once how everyone was grumbling about me, he looked at me — like a father would look at a son — and said sternly: “You’re doing the right thing, let them grumble.” Then he grinned!