The Danish head of a World Health Organization-led team that traveled to China earlier this year to probe the origins of Covid-19 called for closer scrutiny of a laboratory near the site of the first known cluster of cases at a market in the central Chinese city of Wuhan.

In comments broadcast by Denmark’s state-owned TV 2 and confirmed to The Wall Street Journal, Peter Ben Embarek, a food-safety specialist, said investigators should seek more information about the lab, a research facility run by the Wuhan Center for Disease Control and Prevention.

Dr. Ben Embarek’s remarks mark the biggest departure by a member of the WHO’s team from their view, expressed at a news conference in February, that a laboratory incident was too unlikely to merit further studies.

“It’s interesting that the lab relocated on the 2nd of December 2019: That’s the period where it all started,” Dr. Ben Embarek said in the TV interview. “We know that when you move a lab, it disturbs everything…That entire procedure is always a disruptive element in the daily work routine of a lab.”

The Wuhan CDC couldn’t be immediately reached for comment. In February, lab workers told the WHO-led team that there were no incidents or mishaps that could have unleashed a virus.

“The Wuhan CDC lab which moved on 2nd December 2019 reported no disruptions or incidents caused by the move,” the WHO’s joint report said. “They also reported no storage nor laboratory activities on CoVs [coronaviruses] or other bat viruses preceding the outbreak.”

The debate over whether the coronavirus pandemic could have begun with a laboratory mishap has pitted the U.S. against China, and caused deep ruptures between virologists who reach difference conclusions on how likely the idea seems.

The convoy carrying the World Health Organization team tasked with investigating the origins of Covid-19 arrived at the Wuhan Center for Disease Control and Prevention in February.

Photo: thomas peter/Reuters

Chinese authorities, who say the virus couldn’t have come from a local lab, have suggested the pandemic could have started outside its borders.

The WHO team sent to study evidence on where the coronavirus came from was sharply constrained during its four-week trip—with two of those weeks spent in quarantine—and was mostly limited to listening through presentations from Chinese scientists and government officials who declined to provide raw data behind their conclusions.

China says it cooperated fully with the probe, and has encouraged the WHO to study whether the virus first began spreading elsewhere.

WHO Director General Tedros Adhanom Ghebreyesus has called for further scrutiny of labs in Wuhan, and has offered to send experts as part of a second phase of studies. But diplomatic negotiations to conduct that work have stalled in recent weeks in the face of objections by Beijing.

“Searching for the origins of any novel pathogen is a difficult process, which is based on science, and takes collaboration, dedication and time,” the WHO said in a statement. “In order to address the ‘lab hypothesis,’ it is important to have access to all data and consider scientific best practice.”

The Biden administration has ordered U.S. intelligence agencies to conduct a 90-day review of the available evidence. That review is set to wrap up at the end of this month. U.S. officials have warned that it is unlikely to reach a firm determination of whether the virus began with a lab accident, or in nature.

In his televised remarks, Dr. Ben Embarek focused on the Wuhan CDC lab.

The lab is classified BSL-2, a safety level at which air ventilation controls aren’t particularly strict, as they are in more secure labs. At that level, lab workers are usually dealing with pathogens that either cause mild disease in humans or which don’t typically spread through small particles that linger in the air. Researchers at that level don’t necessarily wear masks.

The Wuhan CDC lab tested all of its staff for Covid-19 antibodies, it told the WHO in February. All staff tested negative, except one who tested positive, it said. That person was infected “due to family cluster transmission,” the WHO-led team’s report’s annex says.

There is no mention of whether the tests were carried out early enough to detect antibodies, which can fade over time, and no blood samples were preserved.

But Dr. Ben Embarek is the first to so explicitly question the team’s conclusion, published in a joint report with Chinese counterparts, that a lab accident was an “extremely unlikely” hypothesis.

That wording was only reached after a 48 hour period of intense negotiations with Chinese counterparts said Dr. Ben Embarek, who said he would have preferred to designate an accident inside a lab as merely “unlikely.”

Beyond that, he said he considered it a stronger possibility that a lab worker interacting with bats in nature could have been the pandemic’s patient zero.

“An employee who was infected in the field while collecting samples falls under one of the likely hypotheses,” he said. “That is where the virus jumps directly from a bat to a human. In this case, it would be a lab employee instead of a random villager or another person or some other person who is regularly in contact with bats.”

He said he was intrigued by the fact that the lab relocated just as the pandemic was beginning, and said he only learned about the move after it came up in conversation with Chinese researchers.

The lab hadn’t published any work with bats since 2013, he said.

“That doesn’t mean they haven’t worked with bats since,” he said, in the interview, which he said was conducted around April but held while TV2 awaited clarity on whether future studies will be conducted. “As far as we understand, they work mostly with parasites, not as much with viruses, so they have worked on parasites from bats.”

“It’s also possible that someone is trying to hide something,” he added. “Who knows?”

Write to Drew Hinshaw at drew.hinshaw@wsj.com, Jeremy Page at jeremy.page@wsj.com and Sune Engel Rasmussen at sune.rasmussen@wsj.com