European Union regulators warned British Airways, American Airlines and Iberia Airlines that their plans to share their lucrative trans-Atlantic rules may break antitrust rules. According to the EU, a formal charge was sent to each of the airlines, saying their cooperation may go against the rule that forbids companies engaging in partnerships that shut out rivals.

The airlines said they are planning to apply for antitrust approval from the United States Department of Transportation and that they would also notify the European Union commission. The first effort toward the tie-up was made 12 years ago, when American and British Airways joined their operations.

BA started negotiations with Iberia Airlines, the Spanish carrier, but nothing has been finalized. AA and BA are also considering including Finnair and Royal Jordanian in this partnership.

If they receive the approval, the alliance would service 443 destinations in 106 countries with around 6,300 daily departures. If the deal will get rejected by the EU, the companies may get fined 10% of global annual turnover for forming an illegal cartel.

The EU is also running parallel investigations on other airlines. The Star Alliance (Lufthansa, Continental, United and Air Canada) and SkyTeam (Air France/KLM and Delta/Northwest) are also under its watchful eye. Only airlines alliances that fly trans-Atlantic are currently analyzed.

Even with the alliance of BA, AA and Iberia, these airlines would still be the second-largest airline with 18% of seats, following Delta-Northwest-Air France that own 25%. On Sunday, Virgin announced a $5.6 million marketing campaign against the alliance, including painting 34 of their aircrafts with the message “No Way, AA/BA.” (via Yahoo)