Competition Commissioner Karel van Miert said in Washington that as currently planned, the tie-up threatened to put an end to competition on "several important routes" between the US and London.
The Commission also objects to plans to sell take-off and landing rights at London's Heathrow Airport to rivals if UK regulators order the carriers to part with slots as a condition of approval. "It remains to be seen whether proper remedies can be found," Mr Van Miert said.
In Washington, he met American's chief executive Robert Crandall, who described their talks as "a satisfactory exploration of the opportunities for the transaction to proceed" and predicted that the deal would be go through in the third quarter of this year.
Mr Van Miert also described the proposed merger between Boeing and McDonnell Douglas as "extremely problematic." One way to alleviate the difficulties would be for Boeing to sell some assets after the transaction is completed, he said. The Commission is investigating the competitive implications of the merger and will complete its review by the end of July.Reuse content