Switzerland is set to become the next European country to be subject to quarantine measures by all four nations of the UK.
A seven-day rate of 20 Covid-19 cases per 100,000 people is the threshold above which the UK Government considers triggering quarantine conditions.
Switzerland is currently recording a seven-day rate of 20.7 cases per 100,000.
It will 'almost certainly' be added to the red list this weekend, The Times reports.
Scotland already requires travellers from Switzerland to quarantine for two weeks.
It would be the latest extension of the two-week quarantine rules for all UK arrivals to come into force in efforts to guard against a second wave of coronavirus.
All passengers – bar a handful of exemptions – are required to give contact details and the address where they will isolate.
It comes as France is looking to impose mandatory quarantine on Britons arriving in the country in the coming days.
People who arrived in the UK from France after August 15 are required to self-isolate for 14 days due to rising numbers of coronavirus cases in France.
France's secretary of state for European Affairs Clement Beaune suggested those travelling from the UK to France could soon face similar requirements.
He told France 2: "There will be reciprocal measures so that Britons don't close the border in one direction.
"For travellers returning from the United Kingdom, there will probably be restrictive measures decided in the next few days by the Prime Minister and by the Defence Council."
Croatia, Austria and Trinidad and Tobago were all added to the red lists on August 20, forcing British holidaymakers to pay hundreds of pounds on last minute fights home.