Ryanair has vowed to unconditionally sell its stake in Aer Lingus in an attempt to appease the Competition Commission.
The budget airline's 29.8 per cent shareholding in its Irish rival is under investigation by the CC to see if it is preventing Aer Lingus from merging to remain competitive.
But Ryanair today made an undertaking to the commission that it will sell the stake to any EU-based airline which wants to take over Aer Lingus.
However, the airline made clear its resentment towards the CC's investigation into its Aer Lingus shareholding.
It said in a statement: "In order to dispel the CC's unfounded and invented 'concern' that Ryanair's shareholding may prevent Aer Lingus from being acquired by another EU airline, Ryanair will undertake to unconditionally sell its 29 per cent shareholding to any other EU airline that makes an offer for Aer Lingus and obtains acceptances from 50.1 per cent of Aer Lingus shareholders."
The CC had been due to submit a report on the impact of Ryanair's shareholding in Aer Lingus by July 11. But this deadline has been pushed back to September 5, although the final report is expected to be released next month.
Ryanair has tried three times to take over its Irish competitor - the latest attempt was blocked by the European Commission in February.
Ryanair spokesman Robin Kiely added: "It is clear from the CC’s own provisional findings report that it has found no evidence of any lessening of competition between Ryanair and Aer Lingus.
"In fact, Ryanair's recent offer for Aer Lingus was prohibited by the EU precisely because of the evidence, submitted by both Aer Lingus and the Irish government, that competition between Ryanair and Aer Lingus has 'intensified' during the past six-and-a-half years."