Ryanair chief executive Michael O'Leary has described the UK Government's quarantine rules as a "political stunt" as he claimed thousands of British families are disregarding them to book summer holidays.
People arriving in the UK from today will be asked to give a phone number and address where they will be self isolating for 14 days.
UK nationals have to comply - but anyone arriving from the Republic of Ireland, Channel Islands or the Isle of Man is exempt. Those caught breaking the quarantine in England can be fined £1000 and £480 in Scotland.
O'Leary told the BBC the rules were unenforceable.
He said: "You could be in Sainsbury's, you could be on the beach, you could be on the golf course in the unlikely event the Home Office calls you - all they will have is a mobile number."
During the interview on the Today programme, O'Leary also said the quarantine rules would put EU visitors off coming to the UK but he said his airline had seen thousands of UK families booking flights abroad.
