China on Thursday categorically rejected the WHO's plan for the second phase of coronavirus origin-tracing in Wuhan, especially to probe the lab leak theory, as it dismissed reports that some of the employees of the facility were infected with the deadly virus before it spread to the city and the world.

China will not follow the World Health Organisation's suggested plan on the second phase of COVID-19 origin-tracing, Zeng Yixin, the vice minister of the National Health Commission (NHC), told a media briefing here.

The work plan on the second-phase origins study proposed by the WHO contains language that does not respect science, he said.

China's broadside against the WHO and its Director General Tedros Adhanom Ghebreyesus, who previously won Beijing's praise and support for praising President Xi Jinping's handling of the coronavirus, came after he asked China to be transparent and provide raw data.

"Asking actually China to be transparent, open and cooperate, especially on the information, raw data that we asked for at the early days of the pandemic. We owe it to the millions who suffered and the millions who died to know what happened," he had said.

Zeng said the plan has listed the hypothesis that China had violated lab regulations and leaked the virus as one of the major research objectives, and he was "very shocked" after reading the proposal, state-run China Daily reported.

Instead, the next-phase origin tracing should focus on various regions and countries, he said, reiterating Beijing's oft-repeated claim that the coronavirus broke out in several places in the world and China was the first to report about it in December, 2019 when it emerged in the central Chinese city of Wuhan.

Zeng said he was shocked by the WHO's work plan as it has been compromised by political manipulation and disrespect of scientific facts.

He said China had allowed the WHO experts to visit all places they wanted to go and meet all people they wanted to see early this year, adding that the results of the WHO-China joint study are able to stand the test of time.

"We hope the WHO can carefully consider the advice by Chinese scientists, take investigating the origin of the COVID-19 virus as a scientific question free from political interference, and proactively and properly conduct sustained investigations into the origin of the virus in various countries across the world," the vice minister said.

Zeng also dismissed reports that the three employees of the Wuhan Institute of Virology (WIV), from where the US alleges the virus may have been leaked, fell sick shortly before the first documented cases of COVID-19.

There was zero infection among staff and students at the WIV, he said.

China has also refused to share the details about the hospital admissions, saying it constitutes a breach of individual privacy and the raw data as asked by the WHO comes under the national security regulations.

Liang Wannian, team leader of the Chinese side of the joint expert team of the WHO-convened Global Study of Origins of SARS-CoV-2, said that the study on the origin of COVID-19 should focus on animals and it should be carried out in countries and regions with bat distribution.

Zeng, also the deputy director of the NHC, said at the briefing that the WIV has no man-made viruses and has never conducted gain-of-function research.

The US has been pushing for a probe into the possibility of coronavirus having leaked from the WIV since early 2020. Former US president Donald Trump, who termed the coronavirus as Wuhan virus , had demanded a probe into the lab leak theory.

Trump's successor Joe Biden has asked the intelligence community to redouble its efforts to get to the bottom of the origins of the coronavirus, after new reports raised questions whether it spread from the laboratory in Wuhan.

The probe into the origin of the pandemic was hampered by the lack of raw data, especially on the first days of its spread.

A joint WHO-China team had travelled to Wuhan and spent four weeks visiting various places, including the WIV. It said in its report in March that the virus had probably been transmitted from bats to humans through another animal and the leak of the virus from the lab was an extremely unlikely pathway.

But WHO chief Tedros, while receiving the report, said as far as the WHO is concerned, all hypotheses remain on the table

While rejecting the WHO's second study on the origin, China has mounted a massive campaign at home and abroad to avert any such move to facilitate international investigators to probe the COVID-19 origin in Wuhan.

Chinese Foreign Ministry spokesman Zhao Lijian told the media here on Tuesday that 55 countries have written to Tedros opposing the politicisation of the virus origin issue.

At a WHO member states briefing on July 16, Russia, Belarus, Pakistan, Sri Lanka, Cambodia, Iran, Syria, Burundi, Zimbabwe, Cameroon, Cuba, Venezuela, Bolivia and many other countries spoke up for justice, he said.

They stressed that tracing the origins of the virus is a scientific matter and should not be politicised. The joint WHO-China study report published by WHO should be upheld, he said.

Separately, he said five million Chinese citizens signed an open letter, calling for a probe into the US bio lab at Fort Detrick, Zhao said, adding that the mystery of Fort Detrick remains unexplained and shrouded by suspicions.