Ryanair said the European Commission submitted its objections on Tuesday, but it has not made them public.
The airline still has the opportunity to make more concessions before a final commission decision that is due early next year.
“Ryanair... remains confident that its offer for Aer Lingus will receive competition clearance following any fair assessment by the commission,” the airline said in a statement.
The issuing of a statement of objections is “a standard procedural step,” Ryanair said.
It said it expected the Commission to market test its package of competition remedies.
Ryanair, which already owns 30 per cent of Aer Lingus, had an initial bid turned down by the European Commission on competition grounds in 2007 and dropped a second offer in 2009.
Analysts and investors view its latest €700m bid as a long shot – reflected in Aer Lingus’s shares trading well below the bid price.