Travellers from four new countries – including Croatia – will have to self-isolate for 14 days on arrival in Scotland from this weekend.
Anyone returning from Switzerland, Austria and Trinidad and Tobago will also have to quarantine for 14 days from 4am this Saturday, following a “significant rise” in the number of coronavirus cases across the four countries.
Portugal will, however, be added to the list of destinations where travellers will be exempt from the requirement to quarantine.
All the changes are UK-wide apart from in the case of Switzerland, which currently only applies to travellers on arrival in Scotland.
The latest data show the weekly number of cases per 100,000 for Croatia increased from 10.4 on August 12 to 27.4 on August 19.
The UK Foreign Office has previously said it would look at putting any country with more than 20 cases per 100,000 people on its quarantine list.
It has warned against all but essential travel to Croatia, Trinidad and Tobago and Austria.
Portugal has been added to the travel corridor list following a decrease in confirmed cases of coronavirus.
Justice Secretary Humza Yousaf said he “cannot emphasise enough” that if people choose to travel abroad, they must be aware the quarantine requirements may change while they are away.
He added: “We continue to closely monitor the situation in all parts of the world and assess the scientific evidence.
“We remain in regular discussions with the other three governments in the UK and base decisions on a shared understanding of the available data.
“However, we will not hesitate to take the action we consider necessary to safeguard public health in Scotland, recognising that the level of risk across the four nations may lead to different decisions.
“As I have said previously, we do not make these decisions lightly, but suppressing the virus and protecting public health is vital.”