Ban expressed "tremendous gratitude" yesterday to Haq "for her outstanding service" during a 38-year UN career which has included a wide range of development, humanitarian and peacekeeping roles from East Timor to Sudan, Afghanistan, Malaysia and Laos.
Ban did not name a replacement, and neither he nor his UN spokesman gave a reason for Haq's sudden departure.
Haq, who is from Bangladesh, was the top UN envoy in East Timor until she replaced Susana Malcorra a year ago as undersecretary-general for field support.