A World Health Organization team has emerged from quarantine in the Chinese city of Wuhan to start field work in a fact-finding mission on the origins of the virus that caused the COVID-19 pandemic.
The researchers, who were required to complete 14 days in isolation after arriving in China, left their quarantine hotel and boarded a bus on Thursday afternoon.
The mission has become politically charged, as China seeks to avoid blame for alleged missteps in its early response to the outbreak.
Major questions surround where the Chinese will allow the researchers to go and to whom they will be able to talk.
Yellow barriers blocked the entrance to the hotel, keeping the media at a distance.
Earlier this month, former WHO official Keiji Fukuda, who is not part of the team in Wuhan, cautioned against expecting any breakthroughs, saying it may take years before any firm conclusions can be made on the origin of the virus.
"This is now well over a year past when it all started," he said.
"So much of the physical evidence is going to be gone.
"The memories of people are imprecise and probably the physical layout of many places are going to be different than they were and how people are moving about and so on."
The mission came about after considerable wrangling between the sides that led to a rare complaint from the WHO that China was taking too long to make final arrangements.
China, which has strongly opposed an independent investigation it could not fully control, said the matter was complicated and that Chinese medical staff were preoccupied with new virus clusters in Beijing, Shanghai and other cities.
While the WHO was criticised early on, especially by the US, for not being critical enough of the Chinese response, it recently accused China and other countries of moving too slowly at the start of the outbreak, drawing a rare admission from the Chinese side that it could have done better.
Australian Associated Press