The Irish government said Thursday it has no intention of selling its 21.5-percent stake in the airline, in which Ryanair already owns a 16-percent share, the Telegraph reported.
The surprise offer, which marks a 12-percent premium to Wednesday's closing price of Aer Lingus shares, could still succeed because most of Aer Lingus' shares trade freely.
Ryanair said it would retain the Aer Lingus brand and all its Heathrow slots and the company's chief executive also said he would be happy for Ireland's government to retain its stake in Aer Lingus.
"This offer represents a unique opportunity to form one strong airline group for Ireland and for European customers," said Ryanair Chief Executive Michael O'Leary. "This offer -- if successful -- means both companies will continue to operate separately and compete vigorously in the small number of routes in which we both operate."