Test to release is due to start on or before 15 December, but the government’s Global Taskforce has admitted it “won’t suit every passenger”.

In its report to the prime minister, it said: “The government has therefore been considering whether a model in which the traveller undertakes a self-isolation period before travel, followed by a test, could be adopted with partner countries.

“The objectives of this would be to reopen markets currently closed to UK residents due to other countries’ Covid-19 border restrictions.”

The report added any system “would have to be agreed bilaterally with a partner government”.

The report concluded a self-isolation period of “at least five days” pre or post-departure “must be a core tenet to reduce the risk of onward transmission”.

“We also recognise that, if visitors decide to self-isolate in hotels or other accommodation with other members of the public on site, clear guidance for accommodation providers and engagement with the sector will be required,” it said.