The former prime minister of New Zealand told UNDP staff that she had notified UN Secretary General of her intention to leave.
The former prime minister of New Zealand told UNDP staff that she had notified UN Secretary General Antonio Guterres of her intention to leave the top post on April 19, at the end of her second four-year term.
"It has been an honour and privilege for me to lead UNDP for eight years," Clark wrote in the email addressed to "dear colleagues."
Clark's departure opens up a race to lead the UN's largest agency.
Former British foreign secretary David Milliband, who now heads the International Rescue Committee, has been tipped as a possible successor as has French ecology minister Segolene Royal.
Clark, 66, took the helm at UNDP in 2009 and in April last year launched a campaign to run as UN secretary general, which she lost to Guterres.
The new UN chief is weighing a series of appointments in the coming months to key positions at the world body, but uncertainty over the US stance has slowed down those decisions.
Aside from the new UNDP chief, Guterres will appoint new faces to head the UN peacekeeping department as well as political affairs and may decide to create a new senior post as head of counter-terrorism.
To satisfy US demands for major reforms at the United Nations, Guterres may offer to appoint a US national to head the management department, diplomats said.