Aer Lingus has published an 80-page document telling shareholders why they should reject Ryanair's takeover bid for the national carrier.
The document strongly urges shareholders not to sell their stake to the low-frills airline for four reasons.
It says Ryanair's takeover offer misrepresents Aer Lingus's proven track record of delivering value and ignores the airline's prospects as an independent company.
The document also says Ryanair has significantly undervalued Aer Lingus and its takeover offer is ill-conceived, contradictory and anti-competitive.
Launching the paper today, Aer Lingus chief executive Dermot Mannion said he could not foresee circumstances where the airline's board would approve the Ryanair bid.