Holidaymakers could find officers 'knocking on their door' when they return from abroad, according to Home Secretary Priti Patel.
The European Union will give fully vaccinated tourists the green light to visit resorts - but ministers insisted holidays in Spain and France remain off-limits.
Boris Johnson and Matt Hancock sought to clarify confusion over the "amber list" of countries, including most European destinations, to which travel is allowed but not encouraged.
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The Prime Minister insisted the position was "very clear" and people should only travel to an amber list country "for some extreme circumstance, such as the serious illness of a family member".
The Prime Minister told MPs: "You should not be going to an amber list country on holiday,"
Passengers arriving from amber list countries are required to self-isolate for 10 days and take two tests.
Portugal is the only major EU destination currently on the Government's "green list" for holidays.
Mr Hancock said 30,000 home visits have been carried out in the last week to ensure people are quarantining.
And according to the Daily Mail, officials have the capacity to carry out 10,000 home visits a day.
Priti Patel was asked by the paper whether holidaymakers returning from amber list countries should expect a 'knock on the door' when they got home.
She said: "Yes, people should. There is a service, provision is in place, capacity has been increased for that very reason. People will not go unchecked.
"Significant resources have been put in place – millions of pounds – in terms of the follow-up checking of people around their testing and making sure they stay at home. It has been stepped up."
It was not clear from her comments whether officers knocking on doors would be police or civilian officers employed to do the job.
