France, March 24 -- The world risks returning to the worst days of the global AIDS pandemic following the sudden halt to US foreign aid funding, the UN's top AIDS official said Monday, warning millions would die.

The United States has historically been the world's biggest donor of humanitarian assistance, but President Donald Trump has slashed international aid since returning to the White House two months ago, putting the entire humanitarian community into a tailspin.

UNAIDS executive director Winnie Byanyima said that if the US funding is not reinstated or others do not step in to fill the gap, "there will be an additional... 6.3 million AIDS-related deaths", a 10-fold increase, in the next four years alone.

"You're talking of losing...