Budget airline Norwegian Air said it had received "several inquiries" in the wake of the advance by Aer Lingus and Airways-owner IAG, as it reported a larger first-quarter loss.
Before the news of IAG's interest, Norwegian Air had warned of a bigger loss on the back of higher fuel costs.
"Norwegian has received several inquiries following IAG Group's announcement of its acquisition of 4.6% of the shares in the company," Norwegian said in a statement.
"The Norwegian Board of Directors has established a steering committee and engaged financial and judicial advisors to review the situation, handle relevant inquiries and to safeguard the interests of all shareholders," it added.
The firm's losses before interest and taxes deepened by 31% to 2.2 billion crowns ($276.40m) year-on-year, while its revenues grew by a third over the same period to 7 billion crowns.
Norwegian Air raised 1.3 billion crowns in a share issue to help fund its transatlantic expansion, a still unproven bet on whether a budget airline can replicate the model that worked for European flights.
Shares in Norwegian Air are up 48% since the start of the year thanks to IAG's interest in bidding for the company.
