British Airways has obtained European clearance for its planned merger with Iberia, on the same day as the two carriers secured approval for their transatlantic tie-up with Oneworld partner American Airlines.
The European Commission had examined the potential impact on routes from London to both Madrid and Barcelona.
But it says its inquiries showed the merged airlines would "continue to face sufficient competition from other carriers".
Regulators also studied several short- and long-haul routes on which BA and Iberia each offered one-stop connections, or a one-stop alternative to their partner's non-stop flight.
The Commission says the combined airlines will also face "enough" competition on these routes, and adds that the transaction will not affect competition in the ground-handling, maintenance or freight markets.
As a result, says the Commission, the merger between BA and Iberia will "not significantly impede competition" in the European Economic Area.
BA says the unconditional approval, which follows regulatory clearance from US authorities last month, marks "another important step" towards completion of the merger.
It plans to complete the merger with Iberia by the end of this year.