UK holidaymakers are facing lengthy queues when they land at popular European airports because of tightened border checks, an airline lobby group has warned.
Passengers arriving at airports in Spain, Portugal, France, Italy and Belgium are being forced to stand in immigration lines for "up to four hours", according to Airlines For Europe (A4E).
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The group, which represents carriers including Easyjet, Ryanair and British Airways' parent company IAG, claimed some passengers are missing their flights because of the issue.
New European Union rules introduced following terror attacks in Paris and Brussels require countries to carry out more stringent checks on travellers entering and leaving the Schengen area, which allows passport-free movement across much of the EU.
The change means the 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.
A4E managing director Thomas Reynaert said: "Travellers face long lines and can't get on their flights. Queuing for up to four hours has been the top record these days.
"Airports like Madrid, Palma de Mallorca, Lisbon, Lyon, Paris-Orly, Milan or Brussels are producing shameful pictures of devastated passengers in front of immigration booths, in lines stretching hundreds of metres.
"At some airports, flight delays have increased by 300% compared to last year."
A4E warned that the situation could worsen in the coming weeks as the new regulations have not yet been fully implemented. The six-month period to put the enhanced checks in place ends on October 7.
Mr Reynaert urged the countries affected to "deploy appropriate staff and resources" to carry out the checks.
"Member states need to take all necessary measures now to prevent such disruptions," he added.
A spokeswoman for travel trade organisation Abta said: "New, stricter passport checks are resulting in longer queues at some airports, including Palma, which is already busy due to a significant increase in passenger numbers.
"Tour operators will ensure that customers get to the airport in plenty of time so that they are not in danger of missing their flights.
"However, independent travellers will need to check the situation with their airlines and, where necessary, ensure they factor these longer queuing times into their travel plans when flying in and out of the airport.
"It is also extremely important that border control check points are sufficiently resourced so that queuing times are kept to a minimum."