Transport secretary Grant Shapps told the BBC there is "no guarantee" Malta will permanently remain on the green list this summer.
Appearing on BBC Breakfast on Friday (25 June) after confirming an extension of the UK’s green list late on Thursday (24 June), Shapps said the government was "trying to be as transparent as possible" about the decision-making process behind its traffic light regime.
"If you take Malta, for example, the only country in Europe with a higher [rate of] vaccination than the UK with a very good system of monitoring and sequencing the coronavirus, it looks unlikely to us that’s something [green list status] we will need to change in the very short term," Shapps told BBC Breakfast.
"But, as I’ve explained with the islands, they don’t have the quite same capacity for sequencing the genome and so be aware that things might change quicker or we’ve seen something in the data that makes it a little bit more marginal.
"You’re right to say there are no guarantees. We are just trying to provide the best forward guidance that we can, we’ve seen many times during this virus that things can, and do, change relatively quickly.
"We’re just trying to be as transparent as possible, so people can make their own decisions."
He urged anyone thinking of taking a holiday this summer to purchase travel insurance and ensure their flight and hotel bookings can be changed.
After being asked about the delay to the potential removal of quarantine for fully vaccinated amber list arrivals, Shapps said there were "quite a lot of things" that needed to be resolved before the change could be made.
The government has said more details of this will follow next month, and national press headlines have hinted the policy could be enacted in August.
"The biggest thing is to give people the opportunity to have their second vaccine," said Shapps. "The Joint Committee on Vaccines and Immunisation is yet to decide on whether children should be given the vaccine and we’re waiting for the scientific advice on that so that’s a large category we need to concern ourselves with.
"Then there’s an issue of how do you prove someone has both doses of a vaccine? It’s easy for UK residents, but how do you do it for people from elsewhere who don’t have a system in a place?"
He further added he was "happy for people to travel domestically or abroad" but people must be "aware of the complications" posed by the virus.
The next review of the traffic light categories is due in three weeks time, with a second formal "checkpoint" review of the traffic light regime itself fixed for the end of July.