The World Health Organization on Saturday cited Zimbabwe's anti-tobacco record and efforts against non-communicable diseases as justifications for making President Robert Mugabe a "goodwill ambassador", as International criticism of the move mounted.
The UN health agency, led since July by former Ethiopian health minister Tedros Adhanom Ghebreyesus, has asked Mugabe to serve in the role to help tackle NCDs like heart attacks, strokes and asthma across Africa.
The appointment announced earlier this week in Uruguay has triggered confusion and anger by activists who note that Zimbabwe's healthcare system, like many of its public services, has collapsed under Mugabe's authoritarian regime.
Britain on Saturday joined the widening chorus of critics, calling the decision "surprising and disappointing, particularly in light of the current US and EU sanctions against him."
"We have registered our concerns with WHO Director General Dr. Tedros Adhanom Ghebreyesus", a foreign office spokesperson said in an email.
Mugabe's "appointment risks overshadowing the work undertaken globally by the WHO on Non-Communicable Diseases."
Zimbabwean activist and human rights lawyer Doug Coltart said on Twitter that a "man who flies to Singapore for treatment because he has destroyed Zimbabwe's health sector is WHO's goodwill ambassador."
Mugabe, who is 93 and has been in power since 1980, is in increasingly fragile health and makes regular trips abroad for medical treatment.
UN Watch, a group primarily known for defending Israel at the world body, called the decision "sickening."
"Amid reports of ongoing human rights abuses, the tyrant of Zimbabwe is the last person who should be legitimized by a UN position of any kind," the group's executive director Hillel Neuer said in a statement.
Speaking in Uruguay's capital this week, Tedros had hailed Zimbabwe as "a country that places universal health coverage and health promotion at the centre of its policies to provide health care to all."
WHO on Saturday pointed to Zimbabwe's record and Tedro's desire to engage senior politicians.
"Dr. Tedros has frequently talked of his determination to build a global movement to promote high level political leadership for health," spokesman Christian Lindmeier said in an email.
"Zimbabwe has ratified the WHO FCTC (Framework Convention on Tobacco Control) in 2014 and the government has launched a levy fund for NCDs to generate revenues for health promotion, including NCD prevention and control," he added.
Contacted by AFP in Geneva, WHO's communications department said it was unable to comment further or respond to widening concerns about Mugabe's role.
UN agencies often name high profile personalities as goodwill ambassadors to draw attention to their work, including actress Angelina Jolie with the refugee agency UNHCR.