The UN Migration Agency tweeted: "Today we mourn the loss of a great man a leader and a visionary."
Annan was the first black African to take up the role of the world s top diplomat serving two terms from 1997 to 2006. He later served as the UN special envoy for Syria leading efforts to find a peaceful solution to the conflict.
Annan was awarded the Nobel Peace Prize jointly with the UN in 2001 "for their work for a better organized and more peaceful world". He was married with three children.
--IANS soni/bg
