IAG last month acquired a 4.61% stake in Norwegian as a precursor to formal talks over a potential buyout.

Norwegian later said it had fielded "several inquiries" following IAG’s interest, establishing a steering group and appointing a legal team to handle any bids.

However, on Friday (May 4), the airline said its board had "unanimously rejected" IAG’s two formal bids for a full takeover.

"The board of Norwegian Air Shuttle (NAS) confirms that it has received two separate conditional proposals from IAG Group in relation to an acquisition of 100 percent of the share capital of NAS," said the airline in a statement.

"These proposals were reviewed in conjunction with NAS’ financial and legal advisers, and were unanimously rejected on the basis that they undervalued NAS and its prospects.

"The board of NAS remains fully committed to delivering on its stated strategy, for the benefit of all NAS shareholders."

Norwegian’s decision to move to block an IAG takeover came as the group reported on Friday morning (May 4) its first quarter financials.

IAG said it delivered €280 million profit during the three months to March 31, up €120 million on the same period last year. Its overall revenue, meanwhile, topped €5 billion, up 2.1% on last year.

In a statement on its discussions with Norwegian, IAG said: "On April 12, 2018, IAG announced that it had acquired a 4.61 per cent ownership position (minority investment) in Norwegian Air Shuttle ASA (Norwegian).

"The minority investment was intended to establish a position from which to initiate discussions with Norwegian, including the possibility of a full offer for Norwegian.

"IAG confirms that it has had contact with the Norwegian board regarding a possible offer, without reaching an agreement.

"IAG is currently considering its options in relation to Norwegian."

Neither Norwegian nor IAG have disclosed any sums relating to the takeover.