Britain announced changes to its travel advice from abroad on Thursday, with Brits returning from Croatia, Austria, and Trinidad & Tobago having to quarantine for two weeks.
Meanwhile, Portugal was added to the UK's travel corridor meaning no quarantine is necessary.
Transport Secretary Grant Shapps tweeted: "Data shows we need to remove Croatia, Austria and Trinidad & Tobago from our list of #coronavirus Travel Corridors to keep infection rates DOWN. If you arrive in the UK after 0400 Saturday from these destinations, you will need to self-isolate for 14 days."
"Data also shows we can now add Portugal to those countries INCLUDED in Travel Corridors. As with all air bridge countries, please be aware that things can change quickly. Only travel if you are content to unexpectedly 14-day quarantine if required," he added.
Outlining the basis on which these decisions are taken, Shapps said a range of factors are taken into account, including but not limited to "estimated prevalence of COVID-19 in a country".
The British government also announced on Thursday that six more people died from coronavirus across the UK over the past 24 hours, bringing the total to 41,403. The government added that 1,182 Brits also tested positive over the past 24 hours, bringing the total to 322,280.
