Ethiopia's Tedros Adhanom Ghebreyesus has been elected as the new head of the World Health Organization (WHO), becoming the first African to lead the United Nations health agency.

Ethiopia's former health minister received more than half the votes in the first round and eventually won a decisive third-round election on Tuesday to beat the UK's David Nabarro to the job.

The list of three shortlisted candidates also included Sania Nishtar from Pakistan.

"All roads lead to universal coverage. This will be my central priority," Tedros, as he is widely known, told health ministers at the WHO's annual assembly after his election.

"At present, only about a half of the world's people have access to health care without impoverishment. This needs to improve dramatically."

Tedros was widely seen as having the support of about 50 African votes, but questions about his role in restricting human rights and Ethiopia's cover-up of a cholera outbreak surfaced late in the race, threatening to tarnish his campaign.

Among his critics is prominent Ethiopian long-distance runner Feyisa Lilesa.

"[Tedros] Adhanom is travelling around the world hypocritically talking about health as a human right. But when he was health minister [of Ethiopia], his office refused to acknowledge large cholera outbreaks which cost many lives," Lilesa wrote on Al Jazeera.

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"Adhanom's health ministry [also] used the donor-funded health extension programme as a coercive political recruitment tool for the ruling Ethiopian People's Revolutionary Democratic Front (EPRDF).

"In some cases, people were denied access or were asked to join EPRDF in order to access even the measly services provided by extension workers."

Tedros will begin his five-year term after Margaret Chan, a former Hong Kong health director, steps down on June 30 having spent 10 years in the job.

Chan leaves a mixed legacy after WHO's slow response to West Africa's Ebola epidemic in 2013-2016, which killed 11,300 people.

Six candidates had stood to take the helm at the WHO, which is tasked with combating outbreaks and chronic diseases, before Tedros took the floor at the WHO's annual ministerial assembly.

The job has never before been earned through a competitive election, and health officials from all over the globe thronged the assembly hall in the UN's Geneva headquarters, where voting took place behind closed doors.

Chan, in a speech on Monday, urged ministers to tackle inequalities as a "guiding ethical principle".

"Scientific evidence is the bedrock of policy. Protect it. No one knows whether evidence will retain its persuasive power in what many now describe as a post-truth world," she said.