The head of emergencies at the World Health Organisation reiterated that the group believes the novel coronavirus is natural in origin.
Dr Michael Ryan responded Friday to comments by US President Donald Trump, who said he has seen information that the virus may have emerged from a virology institute in China.
Ryan said WHO teams have listened again and again to many scientists who have looked at the gene sequences and the virus, and we are assured that this virus is natural in origin.
Ryan said it was important to establish the natural host of the virus, which could help pave the way for a better understanding of it and ways to prevent and respond to future outbreaks.
On Thursday, Trump suggested he was confident that China's Wuhan Institute of Virology was at the origin of the coronavirus, before again criticizing WHO's early response to the outbreak.
Most scientists believe the virus emerged at a market in the Chinese city, linked to an animal that has not yet been identified.
The WHO's Emergency Committee on the COVID-19 outbreak recommended Friday that the outbreak remains an international public health emergency, its highest level of alert.