The European Commission has approved IAG's €1.3bn (£940 million) takeover of Irish airline Aer Lingus.
As part of the deal, IAG will have to forfeit five daily slots at London Gatwick for competition reasons.
Two of these slots must be operated between LGW and Dublin, and one between LGW and Belfast. The two remaining slots can be used to serve either Dublin or Belfast.
IAG, which owns BA and Iberia, is also in discussion with airlines that operate long-haul flights out of the UK, the Netherlands and Ireland, committing Aer Lingus to providing them with connecting passengers.