The World Health Organization says the United States government has not given any evidence to support the claims by President Donald Trump and other administration officials that COVID-19 originated in a Wuhan laboratory. Trump has repeatedly said that he has proof the virus originated in a laboratory in Wuhan.

The claims run counter to  the position of scientists who believe the virus jumped from animals to humans at a wet market in Wuhan last year.

The US secretary of state, Mike Pompeo, said on Sunday that the US had “enormous evidence” to back the theory. But the administration had not produced it publicly or provided it to the WHO, said its emergencies director, Dr Michael Ryan. “So from our perspective, this remains speculative,” he said.

“Like any evidence-based organisation, we would be very willing to receive any information that purports to the origin of the virus,” Ryan said, stressing that this was “a very important piece of public health information for future control”.

“If that data and evidence is available, then it will be for the United States government to decide whether and when it can be shared, but it is difficult for the WHO to operate in an information vacuum in that regard.”

Chinese state media attacked the US claims, with the state broadcaster, CCTV labelling them “insane and evasive” in a Monday opinion piece titled “Evil Pompeo is wantonly spewing poison and spreading lies”. The state-backed Global Times also published an editorial accusing Pompeo and Trump of “bluffing”, and said if the US had evidence it should present it.

“If Washington has solid evidence, then it should let research institutes and scientists examine and verify it,” the editorial said.

Around the world infection numbers and fatalities have continued to rise. The death toll has passed a quarter of a million globally, and the US’s daily toll is projected to double by June to 3,000.