European Union antitrust regulators are investigating whether pricing and capacity agreements between Air France-KLM, Alitalia and Delta Air Lines on routes between Europe and North America are bad for passengers.

The European Commission said in a statement on Friday that such deals could breach EU antitrust rules, according to Reuters.

“The goal is to ensure that this tie-up does not harm passengers on EU-US routes,” the Commission said as it announced the start of the investigation.

It said it would consider the implications of the joint venture compared to the situation where the airlines would otherwise be competing.

The agreements signed between the airlines in 2009 and 2010 cover coordinated transatlantic operations in terms of capacity, schedules, pricing and revenues.

“The parties also share profits and losses of their transatlantic flights,” said the Commission, which acts as competition regulator for the European Union.

Alliances allow their members to streamline costs, share revenues and increase scale, a better option for airlines than mergers, which can be difficult and expensive to achieve.

The Commission also said it was closing separate formal antitrust proceedings against several members of the SkyTeam airlines alliance: AeroMexico, Air France and KLM , Alitalia, CSA Czech Airlines, Delta, Korean Air Lines and Continental Airlines, which is part of United Continental.

Meanwhile, Delta Air Lines has reported a higher quarterly profit on Wednesday as fare increases helped offset a 20 per cent rise fuel prices.

Net income came to $425m in the fourth quarter, compared with $19m a year earlier.

Revenue rose eight per cent to $8.4bn. Passenger revenue per available seat mile rose 12 per cent.