Two experts from the World Health Organization will spend the next two days in Beijing, China's capital, to complete ground work as part of a major campaign to trace the origins of the COVID-19 global pandemic.
The United Nations said in a statement that an animal health expert and an epidemiologist will work on a future expedition during their trip aimed at finding out how the virus spread from animals to humans.
Scientists believe the virus originated from bats and then spread to other mammalian creatures such as musk tomatoes or pangolins, and then to the food market in the Chinese city of Wuhan late last year.
To prevent future epidemics from spreading, China acted on wildlife trade and closed some animal markets. The WHO's campaign is politically sensitive because the US that funded it the most has threatened to cut its funding, alleging failure to deal with the epidemic and prejudice to China.
In May, more than 120 countries at the World Health General Assembly called for an investigation to find out the origin of the virus. China insisted that the WHO lead the investigation and wait until the epidemic was under control.