Ryanair has admitted defeat in its renewed takeover bid for rival Aer Lingus, but vowed to fight the decision in the courts.
The low-cost carrier said it had been notified by the European Commission that the 694 million euro (£596.7 million) buyout plan would be rejected.
Ryanair claimed European chiefs were holding it to much higher standards than any other EU airline.
"It appears clear from this morning's meeting that no matter what remedies Ryanair offered, we were not going to get a fair hearing and were going to be prohibited regardless of competition rules," Ryanair spokesman Robin Kiely said. Ryanair said it was told of the decision at a state of play meeting with the EU Commission.
The takeover plan - a third bid by Michael O'Leary for Aer Lingus - appeared to have been boosted last week when Flybe agreed a plan to fly 43 of Aer Lingus's short-haul routes, easing competition concerns.
There had also been a commitment from the IAG airline group to run overlapping Aer Lingus/Ryanair routes between Dublin and London Gatwick to ensure competition.
Mr Kiely said: "Given Ryanair's remedies package clearly addresses every issue raised in the EU's Statement of Objections, any decision to prohibit would be manifestly unfair and in contravention of EU competition rules.
"This decision is clearly a political one to meet the narrow, vested interests of the Irish Government and is not based on competition law."
Ryanair has instructed lawyers to appeal against the refusal in the European courts.
The five worst holiday disasters
Ryanair admits defeat on buyout bid
If you are a victim of a strike, or any other event beyond the airline's control (including ash clouds!), they must offer you a refund (in which case it's up to you to find a way home) or an alternative flight. While you are waiting for the flight you have the right to food and refreshment and accommodation.
If you are on a package holiday, your tour operator is entirely responsible for looking after you until you get back to the UK.
This is more likely to happen due to the financial crisis, but in some situations you are covered.
If you pay by credit card and it's over £100, you'll get a refund from the card company.
Your travel insurance may well cover you too, but check before you go.
Talk to the airline, and if it is temporarily misplaced they should arrange for it to be sent to your accommodation, and you should be either given cash to cover the essentials in the interim.
If it's completely lost you must wait 21 days and then make a claim for compensation. If you are travelling as part of a package you can claim costs from your operator.
If you are travelling within the EU you need an EHIC card, which gives you access to public healthcare. However, this won't necessarily be free, and if you need extra services such as accommodation for a carer, a helicopter home or a delayed flight, you could end up seriously out of pocket.
The only protection that will guarantee you will be looked after without running up a horrendous debt is by having travel insurance - which often covers up to £10 million of costs.
The most common form of theft is pick-pocketing, followed by theft from a car and bag snatching. Meanwhile, 752,000 of those surveyed had items stolen from their hotel room or villa.
If you have anything stolen, your only protection is insurance. You need to tell the local police immediately and get a crime reference for your travel insurer.