All international passengers will soon have to test negative for Covid-19 before travelling to the UK.
People arriving by plane, train or boat, including UK nationals, will have to take a test up to 72 hours before leaving the country they are in.
Transport Secretary Grant Shapps said travellers “can’t board… without having that negative test”.
Mr Shapps said the government was “very keen to do it now” because of the new variant of the virus circulating in South Africa, which he said was “causing great concern with the scientists”.
“They’re not sure whether for example the vaccine will be able to deal with it in the first place, and we’re very, very keen to keep it out,” he told BBC Breakfast.
The new measures are expected to come into force across the UK from next week, and “as soon as possible” in Scotland.
Under the new rules, anyone who arrives in the UK and has not got proof of a negative test could face an immediate £500 fine.
But there will be exemptions for:
All passengers arriving from countries, not on the government’s travel corridor list must still self-isolate for 10 days, regardless of their test result.