Gambia is reported to have expelled a UN envoy after comments she made about the president's HIV/Aids cure claims.
Some patients claim to have put on weight during Jammeh's treatment
Yahya Jammeh said his herbal medicine, taken orally and applied to the skin, cures the disease in three days.
Fadzai Gwaradzimba warned that this treatment could encourage people to engage in risky behaviour, believing that they were cured of the disease.
The United Nationscould not confirm she had been expelled, but says it backs her comments over Mr Jammeh's claims.
Gambia's Daily Observer newspaper said Ms Gwaradzimba "has been given her marching orders because of irresponsible behaviour".
A spokeswoman at the UNDP headquarters said Ms Gwaradzimba would be leaving the country for talks in New York next week.
Ms Gwaradzimba made her remarks in an official statement on 9 February.
Irena Mihova said Ms Gwaradzimba's comments about the herbal treatment were supported by UNDP's senior management.
Later she also spoke to a British journalist who had travelled to the country to report on Mr Jammeh's HIV/Aids treatment.
The president's claims that he can cure Aids in three days have been lambasted by leading Aids specialists who say that it was inconceivable that such a complex disease could be treated in just three days.
President Jammeh said last month he had begun treating 10 patients on Thursdays with the secret medicinal herbal cure.
His health minister backs his claims, saying in trials so far patients had gained weight and physically improved.
Mr Jammeh, who says he can also cure asthma, made his announcement to a gathering of foreign diplomats last month.