Hong Kong will ban all passenger flights from the UK from Thursday amid concern over the Delta variant of the coronavirus.
The Hong Kong government said Britain would be classified as “extremely high risk”.
Under the classification, people who have stayed in the UK for more than two hours will be restricted from boarding passenger flights to Hong Kong.
The rule was issued because of the “recent rebound of the epidemic situation in the UK and the widespread Delta variant virus strain there”, a statement said.
It is the second time the Hong Kong government has banned flights from Britain. Restrictions were also imposed last December, but were gradually eased in April and May as the UK outbreak receded.
Portugal and Spain also imposed new restrictions on British visitors, delivering a further blow to the UK’s traffic light system for travel.
On Monday, Spain said tourists travelling from the UK to Mallorca or Ibiza would have to show proof of full vaccination or a negative PCR test when they arrive.
Portugal’s latest decision, which takes effect on Monday, imposes a quarantine on unvaccinated travellers arriving from Britain.
From Wednesday, UK holidaymakers heading to Malta must also quarantine for 14 days upon arrival if they haven’t had two doses of a Covid-19 vaccine.
Britain added Spain’s Balearic Islands and Malta to its the green travel list last week, meaning travellers from those places will not have to quarantine when they arrive back in the UK.
British ministers plan to ease rules further “later in the summer” to allow people who are fully immunised to return from countries on its amber list without needing to self-isolate.
But Prime Minister Boris Johnson said travel would continue to be difficult for the foreseeable future.
German Chancellor Angela Merkel has suggested the entire EU should co-ordinate closely and be more cautious about allowing travellers to enter from Britain.
The country already has a ban on most travel from the UK, which it describes as a "variant area of concern".