Iberia airline's chief commercial officer said the Spain-based company was now more pessimistic than optimistic about the acquisition of its rival Air Europa after the latest regulatory setback in the €0.5 billion takeover bid.

"We want to keep pushing for this, but the situation has grown ever more complicated," Iberia CCO Maria Jesus Lopez said at an event on the future of aviation held in Madrid.

The UK Competition and Markets Authority earlier this week said it would examine whether the €500m transaction would harm competition in the UK, setting January 19 as the deadline for its initial decision.

IAG said that it would cooperate with the CMA's investigation.

In a previous attempt to secure the deal, Aer Lingus, British Airways and Iberia owner International Airlines Group offered concessions to address EU competition concerns.

The EU executive, which has not provided details in line with its policy, has extended its deadline for a decision on the deal to January 4, casting doubts on whether the bid will go through.