Qatar Airways confirmed Wednesday that it has increased its shareholding in International Airlines Group (IAG) from just under 12 percent to 15.01 percent. Qatar announced the investment update at a global press conference in Atlanta, where the airline celebrated its planned launch of service from Doha on June 1. Atlanta-based Delta Air Lines has been one of the fiercest critics of the three Gulf carriers’ expansion with the help of what it calls state subsidies. Qatar’s investment in IAG—the holding company of Aer Lingus, British Airways, Iberia and Veuling—marks the second such increase in the European airline giant in less than a month.

“We have been very happy with our investment in IAG, from a financial, commercial and strategic perspective,” said Qatar Airways Group CEO Akbar Al Baker. “We have decided to further deepen our relationship with IAG and the increased stake recognizes the strengthening commercial ties between us.

“At Qatar Airways we fully support IAG’s ongoing strategy. IAG is very well positioned in Europe with attractive exposure to the transatlantic segment, leading positions at the London and Madrid hubs and the future benefits from the acquisition ‎of Aer Lingus.”

Al Baker added that Qatar Airways might consider increasing its stake further over time within the allowable limits on non-EU ownership. EU rules allow for no more than a 50-percent share in a European airline by a foreign investor.