In the UK, British Airways, Ryanair and Easyjet are among airlines warning British holidaymakers of delays at EU border controls at many European airports.
British Airways sent texts asking travellers to make sure they arrive early, as the company expects longer queues due to "enhanced immigration checks" across Europe. BA has already sent texts to customers flying back from Lyon, Madrid, Barcelona and Milan. They will follow this advice to all UK bound passengers from most European airports in the next few hours.
Ryanair is also advising customers to arrive at least three hours before their departure time.
Easyjet is urging people to check its website for updates and allow plenty of time to get through the airport. The airline has also warned of strike action due at Barcelona airport every Friday, Sunday and Monday from 4 August throughout the summer.
A spokesman for Airlines for Europe (A4E), the airline lobby group, told the media "It seems the governments - especially in France, Italy, Spain, Portugal and Belgium - underestimated the situation of many passengers going through tighter passport checks and have not provided a sufficient amount of border control officers." He said passengers should expect delays at airports in Majorca, Malaga, Lisbon, Lyon, Brussels, Milan and Paris Orly.
Easyjet advised passengers to check the latest travel information pages on its website, adding that it "strongly recommends" passengers allow some extra time to get through the airport on the way to the gate.
Aviation minister, Lord Callanan, said he will urge his counterparts in Portugal, Spain and Italy to "do all they can to reduce queues and allow travellers to get on with their holidays".
The European Commission deny they are punishing the British because of BREXIT and claim the delays were "the price of security".
The rule changes have been brought in after recent terror attacks in Paris and Brussels mean people entering and leaving the Schengen area, which allows passport-free movement across much of the EU, face more security checks. Under the new measures, details of passengers from non-Schengen countries, such as the UK, are run through databases to alert authorities if they are known to pose a threat. However, many of the recent terrorist attackers have come from within the Schengen area and many doubt these extra security measures will have an impact in eliminating terrorist activity.