The planned tie-up between American Airlines, British Airways and Spain’s Iberia moved a step closer to concluding recently after European competition authorities issued their list of objections to the venture.

Among the competition department’s concerns is the disproportionate grip the three airlines would have on key Europe-to-US routes, including those between London Heathrow and Miami and Dallas.

The carriers argue that the landmark ‘open skies’ pact between Europe and the US has since eased restrictions other carriers had faced in gaining access to Heathrow, a key global gateway. They also point out that many of the largest competitors, including Delta Air Lines and Air France-KLM, have already forged powerful ventures with their transcontinental allies.

The formal communication of concerns marks the start of discussions between the European Commission’s regulator and the carriers.