HIV treatments and other services have been disrupted in 50 countries, he said at a briefing on Wednesday/SCREENGRAB
Programmes to tackle HIV, polio, mpox and bird flu have been affected by the freeze on tens of billions of dollars of overseas aid from the US, says the head of the World Health Organization (WHO).
US President Donald Trump has taken steps to close the United States Agency for International Development (USAID), arguing that its spending is "totally unexplainable".
However, WHO chief Dr Tedros Adhanom Ghebreyesus has urged the Trump administration to consider resuming aid funding until other solutions can be found.
HIV treatments and other services have been disrupted in 50 countries, he said at a briefing on Wednesday.
Speaking publicly for the first time about the freeze on US aid funding at a virtual press conference in Geneva, Dr Tedros said: "There are actions that the US government is taking... which we're concerned are having a serious impact on global health."
In particular, he pointed to the suspension of PEPFAR, the President's Emergency Plan for Aids Relief, which he said had halted HIV treatment, testing and prevention services in 50 countries.
He added that a reprieve for life-saving services had not stopped the disruption.
"Clinics are shuttered, and health workers have been put on leave," Dr Tedros said.
Experts in global health have warned of the spread of disease, as well as delays to the development of vaccines and new treatments as a result of the cuts.
