The government has ruled out plans to issue so-called "vaccine passports" to enable people who have had the jab against coronavirus to travel abroad.
The Greek prime minister has said he would welcome British holidaymakers if they could prove they have been vaccinated.
Vaccine minister Nadhim Zahawi told the BBC's Andrew Marr Show that people could get evidence from their GP.
Labour says vaccine passports may be necessary.
The possibility of giving people "vaccine passports" to allow a return to international travel is being debated in the UK and elsewhere.
Former UK prime minister Tony Blair and Greek leader Kyriakos Mitsotakis are among those calling for their introduction.
In the UK, more than 11m people have been vaccinated against coronavirus so far.