The return of foreign travel to and from the UK will be "gradual and slow" as ministers caution against international trips.
Transport Secretary Grant Shapps said on Thursday that Britain was in no rush to expand the green list of quarantine-free destinations because the country could not risk imported cases of Covid-19.
The remarks came as new analysis suggests up to 270,000 people in the UK will fly to amber list countries despite Prime Minister Boris Johnson’s warning that those nations should be avoided except for extreme reasons.
More than 1,300 flights are scheduled to fly to amber list countries in the five days up to Sunday at a rate of 54,000 passengers a day.
Mr Shapps reiterated that the “amber list and red list are not for holidaymakers”.
"The reason is we think after a year of lockdowns in this country, people coming forward in record numbers to get their vaccines, we don't want to be in a position of taking risks at this stage of our unlock," he told BBC's Radio 4 Today programme.
“It’s a gradual and slow process and I know the public is on our side with this. They want it to be gradual and slow.”
Mr Shapps said the green list of 12 countries and territories would expand when other countries “catch up” with the UK’s vaccination campaign.
He said another major factor influencing the green list was the country’s genome sequencing capability to identify variants of the virus.
“We judge that individually, country by country,” he said.
“Yes, I expect the green list to expand but we are doing this very cautiously and most people support that.”
EasyJet chief executive Johan Lundgren said the UK government appeared to be “dismantling its own system” by discouraging travel to amber list countries.
“It’s absolutely legal to travel to amber list countries,” he said.
“When this was introduced, there was no indication that you shouldn’t travel to these countries because that’s what the restriction was supposed to do. It was there to make sure you could do this in a safe way.”
Forty-three countries are on the red list, requiring British residents to quarantine in an approved hotel for 10 days at a cost of £1,750 ($2,467).
Every other country was placed on the amber list – meaning travellers must quarantine at home on their return for 10 days and take PCR tests on days two and eight.