People arriving into England from 22 Covid-19 hot spot countries including South Africa, Portugal and South American nations will be required to complete a 10-day hotel quarantine.
It comes after the number of Covid-19 deaths in Britain passed 100,000 people yesterday. More than 3.7 million people in Britain have been infected by the virus.
In the House of Commons, Boris Johnson said travellers arriving from those countries must quarantine "without exception", and would be escorted from the airport to the facilities.
"In order to reduce the risk posed by UK nationals and residents returning home from these countries, I can announce that we will require all such arrivals who cannot be refused entry to isolate in Government provided accommodation," he said.
Earlier, the Prime Minister announced another five weeks delay to the reopening of schools in England until at least Monday, March 8.
"It will not be possible to reopen schools immediately after the February half-term. But I know how frustrating that will be for pupils and teachers who want nothing more than to get back to the classroom," he said.
Initially Johnson planned to reopen schools on the week of February 22, but high infection rates and uncertainty over the vaccine’s ability to prevent the spread of the virus, meant the date was pushed back. He provided little detail on how schools will reopen but promised to publish a road map out of lockdown in the middle of next month.
Only vulnerable children and those whose parents are key workers have been permitted to attend primary and secondary schools in person since the third lockdown came into force on January 5. Other pupils have been forced to learn remotely.
Opposition parties have called on the Government to use the half term break to vaccinate teachers to help schools stay open.