China will not follow the World Health Organization's suggested plan on second phase of coronavirus origin-tracing which prioritizes lab leak theory, Zeng Yixin, deputy head of the National Health Commission (NHC), said at a press briefing Thursday.

"I was surprised when I saw WHO's origin-tracing plan for the second phase," he said. "The plan has set the assumption of China leaking the virus due to violating research instructions as one of the research priorities."

Zeng noted that "the plan indicates the disrespect to common sense and the arrogant attitude toward science."

The second phase of origin-tracing should be conducted based on the first-phase conclusions and China opposed politicizing such work, according to Zeng. "No need to conduct repetitive research which have already come to clear conclusions."

Zeng said China respects the report results concluded by all the renowned, experienced WHO experts in March which said the "lab leak" was "extremely unlikely."

"The Chinese government has made it clear that the origin-tracing work must be based on science," he added.

So-called 'gain of function' experiments 'a pure lie'

Zeng clarified several rumors and confusions on the "lab leak theory" involving the Wuhan Institute of Virology (WIV).

He strongly refuted rumors including one about three staff getting sick because of the coronavirus and the other one about the institute conducting so-called "gain of function" experiments on the virus.

"I have been saying this for quite some time. They're a pure lie," he said.

The most similar coronavirus the institute collected from the bats for research before the outbreak was RaTG-13, which shares 96.2 percent homology with SAR-COV-2, a far different one in science, according to Zeng.

A man-made virus is also an impossible assumption, Zeng pointed out. "It's common knowledge to genetic engineers that a man-made virus has traceable marks," he said. "But the novel coronavirus doesn't have any."

Yuan Zhiming, a professor at the WIV and director of China's National Biosafety Laboratory, further dismantled the rumor about the three WIV staff.

It has long been rumored that three people from the WIV went to a hospital for the exact same symptoms as COVID-19 back in November 2019. Based on this rumor, many media outlets concluded that the Chinese government lied about how COVID-19 started to spread in Wuhan.

"If you want the absolute truth, there's a straightforward way," Yuan said at the press briefing. "You only need to ask those media outlets for the names of the three people."

"I've been asking this since a long time ago and no one has replied," he said.

Research papers against the lab leak theory

Yuan also listed three recent research papers that draw conclusions against the lab leak theory.

1. A total of 24 globally renowned experts published a paper on The Lancet on July 5 saying there is not any scientific proof supporting the theory;

2. Scientists from the U.S., UK, Australia and more Western nations uploaded a preprint paper on scientific data-sharing platform Zenodo on July 7 saying there is not any proof that the early COVID-19 cases in Wuhan are related to the WIV;

3. A total of 22 scientists from China and other countries published a paper on research journal Science China "just a few days ago" that explained why the novel coronavirus cannot be man-made based on classical evolutionism theories.

Not providing original data 'a common practice across the world'

On the media accusations that China refused to provide original data to WHO experts, Liang Wannian, leader of the Chinese side of the first-phase tracing team, said it is a common practice in China and other countries.

"The data about the first 174 cases in Wuhan was displayed in its entirety," he said. "The Chinese side and the foreign side of the team examined the data together."

Liang also said the experts were not allowed to take pictures of or copy the data in order to protect the privacy of those COVID-19 patients.

"At that time, the foreign experts said they understood our practice," he explained. "Since it's a common practice not only in China, but also across the world."

On the data security concerns, Yuan added that the WIV's online database was taken down because "the WIV website was under heavy cyberattacks, which was also true for the work emails and even personal emails of Shi Zhengli and other staff."

(CGTN's Wu Guoxiu also contributed to the story.)