Travellers to the UK from Croatia, Austria and Trinidad and Tobago will have to quarantine for 14 days on their return to the country, it has been announced.

Transport Secretary Grant Shapps announced the measures would come into effect from 4am on Saturday.

Meanwhile, passengers arriving in the UK from Portugal will no longer have to self-isolate after it was added to the travel corridor list.

In Scotland, travellers from Switzerland will also be required to quarantine for a fortnight, the country’s Justice Secretary Humza Yousaf announced.

On Thursday afternoon, Mr 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 (I speak from experience!)”

Regarding Scotland’s decision to include Switzerland in its requirements for travellers to quarantine, a Scottish Government spokesman explained that a different position on the virus would mean a different assessment of risk across the four UK nations.

“We are taking hard decisions to safeguard public health and suppress transmission of the virus,” he said.

“There is evidence in Switzerland of a sharp increase in the number of cases, which are now at a similar level to Austria’s, and a number of other countries have taken action to place controls on travellers from Switzerland.

“On the basis of that evidence, Scottish ministers took the decision to remove them from the exemptions list as a precautionary measure.

“While we will try to align on a four-nation basis as far as possible, the different position in relation to the virus means that there will be a different assessment of risk across the nations.”

The weekly incidence (cases) per 100,000 for Croatia has increased from 10.4 on August 12 to 27.4 on August 19 – a 164% increase.

Over the same period, Trinidad and Tobago saw a 232% increase increase in weekly incidence per 100,000, while Austria had a 93% increase between August 13 and August 20 (from 10.5 per 100,000, to 20.3).

The Foreign and Commonwealth Office (FCO) has updated its travel advice to advise against all but essential travel to Croatia, Trinidad and Tobago and Austria, while Portugal has been exempted from the FCO’s global advisory against non-essential travel.

The Government has pledged to take “decisive action” if necessary to contain coronavirus, including removing countries from the travel corridors list rapidly.

Scotland was the only nation of the UK to add Switzerland to its quarantine list.

Mr Yousaf said: “We cannot emphasise enough that if people choose to travel abroad, they must be aware that quarantine requirements may change while they are away.”

In Wales, a written statement by Welsh Government health and social services minister Vaughan Gething said: “I have today met with ministers from across the four national governments in the UK to discuss the potential change to the international travel regulations.

““As a result of that meeting, it was decided to add Portugal and remove Austria, Croatia and Trinidad and Tobago from the list of exempt countries and territories.

“I will tomorrow lay the necessary regulations which will come into force at 4am on Saturday August 22.”

Meanwhile, a 33 year-old with no known underlying conditions is among the latest deaths of people who had tested positive for coronavirus, NHS England announced on Thursday.