Ryanair boss Michael O'Leary has slammed new passport controls which are causing chaos for holidaymakers at some EU airports as he revealed that more than a fifth of the airline's flights were being delayed.
Just 78% of the Dublin-based carrier's flights were on time on Tuesday, down from 90% during the month of August as a whole last year.
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.
Passengers at airports in Spain, Portugal, France, Italy and Belgium are being forced to stand in immigration lines for "up to four hours", according to lobby group Airlines For Europe (A4E).
Ryanair chief executive Michael O'Leary said he is "jumping up and down" in frustration at the disruption.
He told a central London press conference: "Why are these new and more onerous passport restrictions on outbound flights?
"If people are leaving your country, what the hell is the problem?
"They're leaving. Why are you worried?"
He went on: "You're at the peak of the travel period, the UK school holidays.
"We're suffering like most other airlines. Yesterday our punctuality was only 78%.
"A lot of it was because of delayed passengers - not on inbound flights - but delayed passengers on outbound flights getting through outbound passport control.
"Why you're going through outbound passport control in any European country is a mystery to me."
Aviation minister Lord Callanan said he would be speaking to his counterparts in Portugal, Spain and Italy to "urge them to do all they can to reduce queues and allow travellers to get on with their holidays".
He went on: "Clearly it is right that other EU countries have appropriate border controls, but it is also in everyone's interests that tourists are able to start their holidays and spend money across Europe."
Airlines UK, an industry body representing UK-registered carriers, said it had warned the Department for Transport about the problem in May, although they were told by ministers the issue had eased.
Tim Alderslade, the body's chief executive, said: "Clearly the situation has changed markedly as we enter peak holiday season, and it is now up to the UK Government to work with industry to use whatever influence it can within the EU to persuade Schengen member states to resource their border operations properly."
A4E warned 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.
EU commissioner for security Julian King said checking travellers against the EU-wide counter-terrorism and law enforcement databases - which have more than 8,000 terrorists listed - helps to "keep us all safer and more secure".
He added that the system was proposed in 2015 and agreed last year, so authorities have had "lots of time to prepare and put in place the necessary arrangements".