Michael O’Leary, the outspoken chief executive of Ryanair, has said it is “absolutely imperative” that “big tourist destinations” such as Greece and Spain be added to the UK’s green list at the end of this week.

“The restrictions should be lifted, we should be allowing British families to travel to the US and Europe, and also to return without having to complete useless PCR forms for people who’ve already been vaccinated,” Mr O’Leary told Sky News.

But scientists have warned that any increase in international travel could put Britain’s recovery from COVID-19 at risk, with the potential for new variants to enter the country as tourists return from less vaccinated countries.

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“Nothing is absolutely safe,” Mr O’Leary said, but “it is scientists and doctors’ jobs to urge caution and care and worry,” he added. “The vaccines are effective against the Indian variant, it’s a scariant being used by the science and medical professions to urge caution.

“It’s time that we got on with our lives. We’ve had 18 months of the scientists and the doctors worrying us about scariants and variants and all the rest of it.”

Current data suggests that the variant first identified in India is up to 60% more transmissible than the one first identified in Kent.

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The newer Indian variant is “taking over” as the dominant COVID strain in the UK as cases rise across the country, Dr Deepti Gurdasani, a clinical epidemiologist told Sky News.

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Mr O’Leary later acknowledged that the variant was indeed more transmissible, and said he backed a stricter border policy for travellers from southern hemisphere countries.

“There should still be stronger border controls on long haul flights to the southern hemisphere where they have not advanced their vaccine programme,” he said.

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Shapps: ‘Apply common sense over travel’

But the airline boss went on to slam the requirement for vaccinated British travellers returning to the UK from green list countries to produce negative PCR tests, calling the situation “bizarre”.

“There’s no excuse for the government to restrict air travel,” he said. “It’s time to go on holidays and it’s time to fly Ryanair.”