The World Health Organisation (WHO) should overturn its decision to appoint Zimbabwean President Robert Mugabe as a goodwill ambassador, global health leaders say, describing the move as unjustifiable and wrong.
On Saturday, Britain said Mr Mugabe's appointment was "surprising and disappointing" and added that it risked overshadowing the WHO's global work.
The United States, which has imposed sanctions on Mr Mugabe for alleged human rights violations, said the "appointment clearly contradicts the United Nations' ideals of respect for human rights and human dignity".
WHO Director-General Tedros Adhanom Ghebreyesus announced the appointment at a meeting on non-communicable diseases (NCDs) in Uruguay on Wednesday.
The meeting was attended by Mugabe, 93. He is blamed in the West for destroying his country's economy and numerous human rights abuses during his 37 years leading the country as either president or prime minister.
In a speech, Tedros praised Zimbabwe as "a country that places universal health coverage and health promotion at the centre of its policies to provide health care to all".
The former Ethiopian health and foreign minister was elected last May as WHO's first African director-general, added: "Today I am also honoured to announce that President Mugabe has agreed to serve as a goodwill ambassador on NCDs for Africa to influence his peers in his region to prioritise NCDs."
The NCD Alliance said it was "shocked and deeply concerned" to hear of the appointment, given Mr Mugabe's "long track record of human rights violations".
Jeremy Farrar, a leading global health specialist and director of the Wellcome Trust charity also said the decision was "deeply disappointing and wrong" and called on Tedros to be brave and reverse it.
WHO spokesman Christian Lindmeier said the WHO chief had made the move seeking broad support for the agency's work.
Human rights activists also criticised the move.
Hillel Neuer, executive director of the Geneva-based group UN Watch described the choice by WHO, a United Nations agency as "sickening".
He noted that Mr Mugabe himself had travelled to Singapore for medical treatment three times this year rather than in his homeland.