The testing requirement only applies to people flying to English airports, with the government saying that while there are no direct flights from China to Scotland, Wales or Northern Ireland, it is working with the devolved administrations to ensure the policy is applied UK-wide.
The World Health Organization (WHO) has called on Beijing to share “real-time” information on Covid – including on deaths, hospitalisations and vaccinations.
The UN body said it was willing to offer support on data-sharing, adding that it was “understandable” that some countries were now imposing fresh restrictions.
China’s foreign ministry said earlier this week that its “epidemic situation” overall was “predictable and under control”.
The Chinese government is reporting about 5,000 cases a day, but analysts say such numbers are vastly undercounted – and the daily caseload may be closer to one million.
he true toll of daily cases and deaths in China is unknown as officials have stopped requiring cases to be reported, and changed classifications for Covid deaths.
The UK government said its decision was due to a “lack of comprehensive health information shared by China”.
Spain, Israel and South Korea also announced on Friday that they will introduce testing requirements in response to the increasing number of infections in China.
Some scientists have questioned the approach of the UK and US – saying it is better to screen people once they have arrived. Italy and Spain have introduced post-arrival testing.
But not all countries have announced additional controls. Germany has joined Australia and Portugal in saying there will be no new rules yet.