China called the mounting international restrictions on travellers from its territory "unacceptable" on Tuesday after over a dozen countries placed fresh Covid curbs on visitors from the world's most populous nation.
The United States, Canada, Japan and France are among the countries insisting 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 years of hardline restrictions last month, with hospitals and crematoriums quickly overwhelmed.
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But Beijing has pushed ahead with a long-awaited re-opening, last week announcing an end to mandatory quarantines on arrival in a move that prompted Chinese people 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 China could "take countermeasures based on the principle of reciprocity".