Helen Clark

The announcement follows strong criticism by US President Donald Trump's administration, which accused the WHO of being "China-centric", and US formal notification on Tuesday that it was withdrawing from the UN agency in a year's time.

Former New Zealand prime minister Helen Clark and former Liberian president Ellen Johnson Sirleaf have agreed to head the panel, WHO Director-General Tedros Adhanom Ghebreyesus said.

RNZ reports the former Portuguese prime minister is poised to take up the role after none of the five UN Security Council veto powers voted against him in a sixth secret ballot, diplomats said.

Helen Clark ended up fifth overall but three of the permanent Security Council members voted against her, effectively vetoing her selection.

RNZ reports with the withdrawal of Montenegro's Foreign Minister Igor Luksic, the field has now narrowed to 10.

In the second straw poll earlier this month Ms Clark was pushed back to seventh place; down from sixth after the first vote.

Ms Clark described the result as disappointing but Prime Minister John Key and Foreign Minister Murray McCully, who have been lobbying hard for her, said she was not yet out for the count.

New Zealand Herald reports the former New Zealand Prime Minister slipped from sixth place to seventh place out of 11 candidates.

Clark hinted in a tweet she would be reconsidering her candidacy: “Disappointed by outcome. Will discuss over coming days.”

New Zealand Foreign Minister Murray McCully said any decision was entirely over to Clark.

It was clear from the increase in "discourage" votes for almost every candidate, that once a country had decided on a first preference, they had tried to discourage others to advantage their first preference.

The former prime minister appeared before the United Nations General Assembly early on Friday morning (NZ time) to detail what she'd bring to the organisation's top job.