UNITED NEWS INTERNATIONAL (UNI) — World leaders have paid tribute to former United Nations chief Kofi Annan, who died over the weekend “after a short illness.”

The Kofi Annan Foundation announced he “died peacefully” on Aug. 18 in Bern, Switzerland. He was 80 years old.

In Annan’s home country of Ghana, President Nana Akufo-Addo declared a week-long of mourning.

UN Secretary-General Antonio Guterres said Annan’s “legacy as a global champion for peace will remain a true inspiration for us all.”

Former President Barack Obama, the United States first black president, said Annan “never stopped his pursuit for a better world.”

Annan was UN Secretary-General from 1997 to 2006 and the only black African to ever hold the post.

Annan dedicated himself to finding solutions to conflicts in Africa, the Middle East and Asia, and championed human rights in the UN that would later win him the Nobel Peace Prize.