The investigation means Ryanair’s €694m (£549.5m) offer for its Irish rival lapses, though the airline said it plans to make a new bid for Aer Lingus if it gets clearance from Brussels.
The Commission, which now has until 14 January to investigate the offer, said yesterday it has concerns that on Irish routes, the “barriers to entry appear to be high. Many of these routes are currently only served by the two airlines”.
It added that the overlap between the two firms’ operations has increased since 2007, when the European authorities blocked a previous bid by Ryanair.
But Ryanair has argued that the aviation industry has changed dramatically since its earlier bids, as shown by Europe’s green light for IAG’s acquisition of BMI earlier this year.
A UK Competition Commission probe into Ryanair’s existing 30 per cent stake in Aer Lingus is ongoing.