Even after experts from the World Health Organization carried out investigation into facilities in Wuhan, from which the virus is suspected of having spread in late 2019, distrust of the Chinese Communist Party has yet to be dispelled both at home and aboard.

Many people, including a political leader of a democratic country, have criticized China for attempting to conceal key aspects of the virus outbreak by pretending to be a savior to other nations that have been still suffering the pandemic.

"Everybody thinks no evidence can be found as one year has already passed" since the start of the epidemic, Shusei Tanaka, a former Japanese lawmaker and political expert at Fukuyama University, said in a TV program.

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"Vaccine diplomacy is not a bad idea, but I want China to contribute more to clarifying the sources and infection routes" of the virus that causes the COVID-19 disease, Tanaka added.

After quarantining for two weeks, the WHO team began a full-fledged probe in Wuhan in late January.

In February, they visited a research laboratory, from which the new virus was rumored to have accidentally escaped, after conducting a one-hour investigation into a market, where many people were confirmed to have been infected in the early days of the outbreak.

One WHO expert from Russia, Vladimir Dedkov, was quoted by the country's state-run media as saying it is "hard" to imagine the virus was leaked from the laboratory and there is "no evidence" that it originated from the market.

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Peter Ben Embarek, the leader of the WHO team and a food safety specialist, also told a press conference on Tuesday following its joint probe with Chinese experts that the virus most probably jumped to humans via an intermediary species.

The administration of former U.S. President Donald Trump advanced a theory that the Wuhan Institute of Virology might be the birth of the virus, but China has rejected the allegation, further exacerbating relations between the world's two powers.

Meanwhile, the market, where wild animals such as bats and snakes had been sold alongside seafood, has been closed since January 2020, and it has been sanitized thoroughly by Chinese authorities.

"It is very easy for China to erase evidence before the WHO arrived," a diplomatic source in Beijing said. "How can we trust what China says, given its initial response to the virus spread?"

The leadership of Chinese President Xi Jinping has been believed to have issued a gag order on health care officials to contain backlash from citizens in Wuhan.

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Local sources told Kyodo News that the Chinese government warned doctors, who responded to the virus in the early stage of the epidemic in the city, that they could be punished for espionage if they revealed what went on during the period.

The Global Times, a tabloid affiliated with the ruling Communist Party, called for "similar field studies on the origins of the novel coronavirus in other countries," arguing that Wuhan is "just the first stop of such scientific work in the world."

China, however, has apparently strengthened online restrictions on remarks about the pandemic, while pushing a propaganda campaign aimed at giving the impression that the virus was conveyed to Wuhan from another nation -- the United States or a European country.

On a social media platform in China, the "novel coronavirus" has been designated by the Communist-led government as a "sensitive word," sources familiar with the matter said.

A taxi driver in Beijing said in a stern voice, "China is a victim of the coronavirus. We know many people caught a mysterious cold in the United States before the outbreak erupted in Wuhan."

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"We are proud that China will become a rescuer by providing vaccines to other nations," the driver said.

As the increase in new infections peaked in late February last year due largely to the Communist Party's radical "zero corona" policy, the world's second-biggest economy became the only major country to attain positive growth in 2020.

On the back of economic recovery, China has approved its home-developed coronavirus vaccines and started to donate them to emerging nations in Asia and Africa, such as Myanmar, the Philippines, Sierra Leone and Zimbabwe.

China appears to be eager to forge ties with these countries through vaccine diplomacy and bolster its global influence at a time when its escalating tensions with the former Trump administration have been dividing the world into two blocs.

Nevertheless, fears linger over the safety and efficacy of China's COVID-19 vaccines, amid skepticism that Beijing may not be disclosing necessary information about them.

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French President Emmanuel Macron said at an event hosted by a U.S. think tank last week that he has "absolutely no information" about the vaccines developed by Chinese pharmaceutical companies.

"What it means is that on the medium to long run it is almost sure that if this vaccine is not appropriate it will facilitate the emergence of new variants, it will absolutely not fix the situation of these countries," Macron said.

Although he conceded China has achieved "diplomatic successes" in distributing vaccines to other nations, Macron added this could be seen as "a little bit humiliating for us" as Western leaders.

Rebuffing Macron's accusation, Chinese Foreign Ministry spokesman Wang Wenbin told reporters that Beijing has "always given top priority to the safety and efficacy of the COVID-19 vaccines."

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"China has never excessively promoted its vaccines. The international community should work together on vaccines, instead of competing against each other," Wang said.

The novel coronavirus has infected more than 106 million people and killed over 2.3 million across the globe so far, a tally by Johns Hopkins University showed.