President Donald Trump said that his administration was trying to determine where the deadly disease originated from, and Secretary of State Mike Pompeo calling on Beijing "to come clean" on what it knows.
At a White House news conference on Wednesday, Trump was asked about the reports of the virus escaping from a laboratory in Wuhan, where the coronavirus first appeared.
"We are doing a very thorough examination of this horrible situation that happened," he said.
Asked if he had raised the subject in his conversations with Chinese President Xi Jinping, Trump said: "I don't want to discuss what I talked to him about the laboratory, I just don't want to discuss, it's inappropriate right now."
At least 136,000 people around the world have now died from the disease, with almost 31,000 in the US alone. More than two million people have been diagnosed with the virus, while at least half a million have recovered.