GENEVA: The World Health Organization (WHO) was electing its new leader Tuesday, with the race narrowed to two finalists who have vowed to shake up the fiercely criticised agency.

After one round of voting WHO member states eliminated former Pakistani health minister, Sania Nishtar, several diplomats with direct knowledge of the closed-door result told AFP.

That left former Ethiopian health minister Tedros Adhanom and British doctor and UN veteran David Nabarro as the remaining candidates to succeed Hong Kong-born Margaret Chan as the UN?s global health boss.

A second round of voting was set to begin shortly.

Chan?s decade-long tenure which ends on June 30 was notably marred by condemnation of the agency?s response to the Ebola epidemic in West Africa.

The WHO was accused of missing key warning signs about the severity of an outbreak that began in December 2013 and ultimately killed more than 11,000 people.

"We know that the next health emergency is not a question of ?if? but ?when?", US health secretary Tom Price said in Geneva before voting was to start.

"When it happens the world will turn to the WHO for guidance and for leadership. We need to be sure it is up to the task," he told the Swiss Press Club