According to Gauden Galea, it is highly important to study the origins of the virus to prevent such outbreaks in the future.
"We know that some national investigation is happening but at this stage we have not been invited to join", Galea said on Thursday.
According to the WHO official, the organization is not able to investigate documents from two virus laboratories in the Chinese city of Wuhan, the epicenter of the outbreak. However, Galea stressed that the WHO had no doubts that the virus occurred in a natural way.
"From all available evidence, WHO colleagues in our three-level system are convinced that the origins are in Wuhan and that it is a naturally occurring, not a manufactured, virus", Galea added.
The new coronavirus was first identified in the Chinese city of Wuhan, Hubei province, last December, later spreading to the rest of the world. On 11 March, the WHO declared the COVID-19 outbreak a pandemic.
To date, more than 3.2 million people have been infected with the coronavirus worldwide, with over 233,000 fatalities, according to Johns Hopkins University.