ONE of the world's most celebrated diplomats, Kofi Annan, has died at the age of 80.

Mr Annan was considered a charismatic symbol of the United Nations, and rose through its ranks to become the first black African secretary-general.

His foundation announced his death in a tweet today, saying he died after a short, unspecified illness.

Mr Annan spent virtually his entire career as an administrator in the UN.

He served two terms as secretary-general from January 1997 to December 2006, capped nearly midway when he and the UN were jointly awarded the Nobel Peace Prize in 2001.

When he departed from the UN, he left behind a global organisation far more aggressively engaged in peacekeeping and fighting poverty, setting the framework for the UN's 21st Century response to mass atrocities and its emphasis on human rights and development.

Antonio Guterres is the current secretary-general of the UN, and said: "Kofi Annan was a guiding force for good."

"It is with profound sadness that I learned of his passing. 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."

Mr Annan returned to the UN in special roles, including as the UN-Arab League's special envoy to Syria in 2012.