GENEVA — The World Health Organization’s emergencies chief said Monday that it has received no evidence from the U.S. government to back up allegations by President Donald Trump and Secretary of State Mike Pompeo that the coronavirus could have originated at a laboratory in the Chinese city of Wuhan.

“From our perspective, this remains speculative,” Dr. Michael Ryan told reporters in Geneva. “We have not received any data or specific evidence from the U.S. government relating to the purported origin of the virus.”