Spain has become the second European nation to announce new COVID restrictions for travellers from China following a surge in cases in the East Asian country.
To enter Spain, passengers will need to have a negative test result or be fully vaccinated.
It comes after Italy earlier this week said it had ordered COVID antigen swabs and virus sequencing for all travellers coming from China.
In the UK, ministers have said the government is keeping the situation "under review". Health minister Will Quince said the "key threat" was the potential for the emergence of new variants.
But Professor Andrew Pollard, the chairman of the Joint Committee on Vaccination and Immunisation, said the imposition of travel restrictions was unlikely to prove effective in stopping variants reaching the country.
"Trying to ban a virus by adjusting what we do with travel has already been shown not to work very well. We have seen that with the bans on travel from various countries during the pandemic," he told the BBC Radio 4 Today programme.
Coronavirus infections have risen sharply across China in December after Beijing scrapped its zero-COVID policies, including regular PCR testing on its population.
China said this week that it would end mandatory quarantine on arrival, prompting many Chinese people to make plans to travel overseas.
And there are fears that the end of almost three years of strict measures in the country of 1.4 billion people could result in a massive spread of the disease worldwide.
But the European Union's health agency said on Thursday it believed the introduction of mandatory COVID screenings of travellers from China was "unjustified".
Outside the EU, countries bringing in new curbs such as mandatory testing include the US, Japan, India, Taiwan and South Korea.
However such measures are not necessary for the EU as a whole, said the European Centre for Disease Prevention and Control (ECDC) in a statement.
On Friday, Malaysia announced it will screen body temperatures of all inbound travellers, including those from China, and those detected with fever or other symptoms will be tested for COVID.
It will also sample wastewater from aircraft arriving from China for coronavirus and will conduct tests to detect the entry of any new variants.
Countries imposing restrictions or considering controls cite a lack of information from China on variants and are concerned about a wave of infections.
China has rejected criticism of its COVID data and said it expects future mutations to be potentially more transmissible but less severe.