China has described the extension of international restrictions on travellers from its territory as "unacceptable" as countries including France, Japan, India and the United States impose Covid controls on visitors from the world's most populous nation.
More than a dozen countries are now insisting that all travellers from China provide negative Covid tests before arrival, as concerns grow over a surge in cases.
China's steep rise in infections comes after Beijing abruptly lifted hardline restrictions last month, with hospitals and crematoriums quickly overwhelmed.
Despite that upsurge in the number of cases, Beijing has pushed ahead with the re-opening, announcing an end to mandatory quarantine on arrival in a move that prompted many Chinese to plan trips abroad.
"Some countries have taken entry restrictions targeting only Chinese travellers," foreign ministry spokesperson Mao Ning told a regular briefing.
"This lacks scientific basis and some practices are unacceptable," she added, warning that China could take countermeasures.
Borne defends French demands
French Prime Minister Elisabeth Borne has defended the new rules.
"I think we're performing our duty to protect French people in asking for tests," Borne told a radio news channel.
"We're respecting the rules of the World Health Organisation, and we will continue to do it."
Since Sunday, travellers from China arriving in France must wear a mask and be prepared to submit to a test on arrival. Tests are being done at random.
From Thursday, all travellers will be required to present a negative PCR or antigen test carried out less than 48 hours before their flight.
French authorities have described the testing regime as a means of tracking variants that might be spreading in China since the country lifted its strict Covid-19 restrictions.
"Our objective, and the scientists agree on this point, is to follow the evolution of the virus and that's what we've been doing since Sunday," Borne said.
European nations are seeking to coordinate their responses, with France, Italy and Britain testing arrivals while other states such as Germany have no restrictions at present.
People arriving in the UK from China will not be required to self-isolate, even if they test positive for Covid-19, the transport ministry has said. The tests on arrival are intended to track new variants, the health secretary has explained, not penalise visitors.
Worries about Chinese statistics
The rules imposed affect all travellers coming from China, not just Chinese nationals. Beijing continues to restrict inbound visitors and refuses to issue visas for tourists or international students.
The United States have cited Beijing's lack of transparency about infection data and the risk of new variants as a reason to restrict travellers.
China has recorded only 22 Covid deaths since December and has dramatically narrowed the criteria for classifying such deaths. This has given rise to fears that Beijing's statistics for the current wave are unreliable.
Medical officials in Shanghai say 70 percent of the city's population of 25 million people have probably been infected.
It is believed that 250 million people were infected in China in the first 20 days of December.
Inefficient vaccines
Chinese officials are now readying for a virus wave to hit the country's under-resourced rural interior, as millions of people prepare to travel to their hometowns for the week-long Lunar New Year public holiday which begins on 21 January.
The United States and other countries have offered to send millions of mRNA vaccines to China, in an effort to help slow the spread of the pandemic.
Chinese vaccines, based on older technology than most European treatments, are believed to provide less efficient long-term protection.
The authorities in Beijing have refused all such offers.
