Experts discussed virus lab theory with Chinese scientists: WHO leader

World Health Organisation inspectors had "very frank" discussions with Chinese scientists about the source of the pandemic, including theories it leaked from a laboratory, the head of the probe in Wuhan told AFP Thursday.

The talks covered famous claims widely reported in global media, Peter Ben Embarek said in an interview a day after he and his WHO team visited the lab.

While he did not identify specific theories, Ben Embarek described some of them as irrational and insisted the investigators would not waste time chasing the wildest claims.

"The discussions were very frank," the food safety scientist with the UN health agency said by telephone from Wuhan, the central Chinese city where the coronavirus was first detected in December 2019.

"We discussed... a lot of the famous theories and so on, and what has been done to explain them," added Ben Embarak, who was based in the WHO's Beijing office for two years from 2009.

Since emerging from a 14-day hotel quarantine last week, the WHO experts have visited a number of high-profile sites linked to the pandemic origins, including a seafood market where people were first found falling ill.

The trip on Wednesday to the Wuhan Institute of Virology was one of the highest-profile events on the agenda because of the controversial theory it was the source of the pandemic.

Scientists at the laboratory conduct research on some of the world's most dangerous diseases, including strains of bat coronaviruses similar to Covid-19.

Speculation emerged early in the pandemic that the virus could have accidentally leaked from the lab in Wuhan, although there was no evidence to back up that theory.

Then-US president Donald Trump and his supporters seized on those rumours and amplified them with conspiracy theories that China deliberately leaked the virus.

No 'chasing ghosts'

Ben Embarek said discussions at the lab were useful to understand the staff's position "in regards to many of these statements and claims that everyone has seen and read about in the news".

He appeared to dismiss some of the theories, calling much of the speculation "excellent scenarios for good movies and series for the years to come".

He also emphasised the WHO investigators would "follow science and we follow facts" in reaching their conclusions.

"If we start following and chasing ghosts here and there, we'll never move anywhere," he told AFP.

"So that's also an important step that we were also able to understand where these stories are coming from.

"And we are able to, in a rational way... explain why some of them are totally irrational, why some of them could make sense, and why some of them can be explained or not explained," he said.

The team visited the institute's P4 lab -- Asia's first maximum-security lab equipped to handle Class 4 pathogens such as Ebola.

Ben Embarek said the trip to Wuhan, which is due to conclude within the next week, would not lead to a final conclusion on how the virus jumped from animals to humans.

"We're not going to come up with the ultimate full understanding of the origins of this virus, but it will be a good first step," he said.

"It will be a very robust and clear best way we will lay for how to move forward."