British Airways-owner IAG may have to offer concessions after EU anti-trust regulators expressed concerns over a planned acquisition of 25 per cent of Ireland's Aer Lingus, two people familiar with the matter said.

IAG is looking to expand lucrative transatlantic services from Dublin airport with the deal. Dublin offers spare capacity, unlike London's Heathrow, where British Airways, IAG's biggest unit, is based.

IAG met with European Commission officials on Wednesday in a so-called state of play meeting. The EU executive typically holds such meetings only if it is concerned mergers may reduce competition.

"It is not particularly likely that IAG will get approval without concessions," one of the sources said.

The second source said IAG was considering whether to offer concessions. It has until next week to do so.

The company is likely to use the time until the deadline to convince regulators that the deal does not pose competition issues and there is no need to offer concessions.

If it does not succeed and still declines to offer concessions, the deal could face a full-scale investigation lasting 90 working days.

Commission spokesman Ricardo Cardoson declined to comment. An IAG spokeswoman said: "Discussions are ongoing and it would be inappropriate to comment further."-Reuters