More than 20 million people have signed an online letter to the World Health Organization demanding a thorough investigation into a secretive United States laboratory tainted by a poor safety record in order to gain a better understanding of the origins of the coronavirus.

Chinese Foreign Ministry spokesman Zhao Lijian has called on the US to respond to the appeal of the Chinese netizens, and allow experts from the WHO to conduct investigations into the origin of the novel coronavirus in the US, including in the Fort Detrick lab.