Laboratory accidents “happen” and are “common”, the head of the World Health Organisation has said as he called on China to be more transparent about the origins of COVID-19.

WHO Director-General Tedros Adhanom Ghebreyesus said there had been a “premature push” to rule out a theory that the virus escaped from a Chinese government lab in Wuhan, where the first human infections were discovered.

His comments appear to contradict a WHO report published in March, which said a laboratory leak was “extremely unlikely”.

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March: Lab leak COVID origin ‘unlikely’

“I was a lab technician myself, I’m an immunologist,” Dr Tedros said. “I have worked in the lab, and lab accidents happen. It’s common.”

It is important to establish whether a laboratory had any role in the pandemic, he said, appealing to China to be “transparent, open and to cooperate, especially on the information – raw data that we asked for at the early days of the pandemic”.

He added: “We need information – direct information on what the situation of this lab was before and at the start of the pandemic.

“If we get full information, we can exclude (the lab connection).”

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German Health Minister Jens Spahn echoed those words, saying Chinese cooperation to date was “not yet enough”.

While many scientists believe COVID-19 may have originated in bats, the precise route it used to reach humans is yet to be determined.

It can take decades to narrow down the natural source of an animal virus such as Ebola or SARS.

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February: ‘I think we’re really getting somewhere,’ says WHO expert in China

In recent months, however, the idea that COVID began in a laboratory, and may have been engineered, has gained traction.

In May, President Biden ordered a review of US intelligence to assess that possibility.

China has rejected those claims, arguing that they are politically motivated and suggesting the pandemic may have started abroad.

It said at the WHO’s annual meeting of health ministers in the spring that there should be a search for COVID’s origins in other countries.

Experts are sceptical that the WHO will get the information it is asking for.

Professor Lawrence Gostin from Georgetown University, who specialises in public health law, said the WHO has “no powers or political heft to demand access to information critical for global health”.

He added: “All Dr Tedros can do is use the bully pulpit, but it will fall on deaf ears.”