Portugal and Malta have introduced measures to restrict UK travellers who are not fully vaccinated.
The Portuguese government says travellers will have to quarantine for 14 days unless they can prove they received their second vaccine dose a fortnight before arrival, reports BBC.
Malta is also only allowing double-vaccinated people in from Wednesday.
In Spain, UK travellers need to prove they are fully vaccinated, or provide a negative PCR test on arrival.
Hong Kong is to ban all passenger flights from the UK from 1 July, after the government said it had discovered cases of “variant virus strains” had been “persistently” detected from the UK in the past few days.
The measures have been introduced for UK travellers, in particular for those not fully vaccinated, amid fears they could spread the Delta variant of coronavirus, which was first established in India.
The Portuguese government added the UK to the list of countries from which travellers must quarantine “at home or a place indicated by the health authorities”. The rules came into effect at midnight.
The new quarantine measures apply only to those travelling to mainland Portugal, not Madeira.
There were 19 flights listed as departing on Monday from UK airports to Portugal’s mainland airports – Lisbon, Faro and Porto.
Brazil, South Africa, India and Nepal were already on Portugal’s quarantine list, but the exception for people who are vaccinated against Covid-19 to avoid isolating applies just to the UK.