Portugal has been removed from the UK safe travel list in a move the government said would safeguard public health against variants of concern and protect the Covid-19 vaccine rollout.
The destination will be added to the amber list.
Seven countries – including Sri Lanka and Egypt – have also been added to the red list.
All changes to the lists will come into effect at early on Tuesday.
The decision to move Portugal (including Madeira and the Azores) to the amber list follows increased concern in the spread of variants of coronavirus, including a mutation of the Delta (India) variant, and the risk that is posed of bringing these back to the UK if people are not required to quarantine.
The situation in Portugal has required swift action to protect the gains made with the vaccine rollout, officials said.
There has been an almost doubling in the Covid-19 test positivity rate in Portugal since the first review for traffic light allocations, far exceeding the ONS estimated national positivity rate in the UK.
More significantly, according to data published on GISAID, 68 cases of the Delta variant of concern have been identified in Portugal, including cases of the Delta variant with an additional, potentially detrimental, mutation.
Transport secretary, Grant Shapps, said: “The public has always known travel will be different this year and we must continue to take a cautious approach to reopening international travel in a way that protects public health and the vaccine rollout.
“While we are making great progress in the UK with the vaccine rollout, we continue to say that the public should not travel to destinations outside the green list.”
The full list of additional countries added to the red list includes Afghanistan, Bahrain, Costa Rica, Egypt, Sri Lanka, Sudan, and Trinidad & Tobago.
For countries going on the red list today, Covid-19 prevalence is assessed to be high and there is evidence to suggest community transmission of variants of concern.
UK Health Security Agency chief executive, Jenny Harries, said: “Increases in case rates in the UK serve as a reminder that this pandemic is not over yet and we need to take a cautious approach.
“Everyone should observe the travel guidance, continue to follow hands, face, space and fresh air, and have both doses of the Covid-19 vaccine when offered.
“Testing will help to break chains of transmission and allow us to see which variants are circulating so make sure you get tested when you return to the UK in line with the guidance.”
Virginia Messina, WTTC senior vice president, said the decision could prove extremely detrimental to the sector.
She added: “The World Travel & Tourism Council shares the huge disappointment of tourism businesses up and down the country, as well as that of holidaymakers, that the government has once again cold-shouldered tourism by refusing to add any new destinations to the already slim green list.
“There are so many countries with similar vaccination levels and low infection rates as the UK to which travel should be restored immediately, such as the US and Malta .
“It is essential we kick-start the return of international travel to save the flailing aviation industry and the global tourism sector.”