China has overcome difficulties to facilitate two trips undertaken by international experts in the country during the COVID-19 outbreak, setting an example for global cooperation and openness, a Foreign Ministry official said on Friday.

The World Health Organization has dispatched two teams of experts to visit China since the epidemic broke out. The trip last February aimed at expanding knowledge on effective disease control measures, and the other from Jan 14 to Feb 10 strove to enhance understanding of the virus' origins.

Yang Tao, director-general of the ministry's Department of International Organizations and Conferences, said at a briefing that during these visits China was coping with local outbreaks or infection clusters, and some experts had to be pulled from the frontline to join the mission.

By addressing challenges and organizing the two visits, China has played an exemplary role in implementing resolutions adopted by the World Health Assembly, he said.

"It shows that China has always been open and transparent. China's prevention and control efforts are conducted in the sunshine, and there is nothing to hide," Yang said.

However, following the recent trip, a handful of countries have jumped to attack WHO experts for patronizing China and conspired to sign a joint statement objecting to an upcoming final report summarizing findings from the trip.

"Such acts are a politicization of scientific questions and a double standard," Yang said.

"Political manipulation will damage the global battle against the disease and may result in more lost lives, which is extremely immoral."

The briefing in Beijing was attended by diplomats from about 50 countries, the Arab League and the African Union.

Feng Zijian, deputy director-general of the Chinese Center for Disease Control and Prevention, said on Friday that experts participating in the recent visit have all agreed the mission had progressed smoothly as planned and they reached their goals.

The team concluded during an earlier briefing that the virus most likely first appeared in humans after spilling over from an animal, and the theory that the virus leaked from laboratories is extremely unlikely.

Feng said that to pinpoint the origin of the virus, it is significant to launch a global search for early infections and early cases testing positive for the virus.

More sampling and testing of bats and other animals susceptible to the virus should be implemented across the globe. The role of cold-chain and cold products in aiding virus transmission is worth exploring further, he said.

Yang added that China is willing to continue cooperation with the international community and will provide assistance within its capacity.

As the first major economy to declare COVID-19 vaccines a global public good, he said, China will not impose export restrictions on vaccines and will help boost vaccine accessibility in developing countries.

The latest data from the National Health Commission show that by Thursday, more than 91.3 million COVID-19 vaccine doses had been administered nationwide, up by nearly 5.5 million from Wednesday.