British Airways, American Airlines and Spain's Iberia have been warned by the European regulators that if their much touted and speculated Transatlantic tie-up is to go forward, they will have to give up on much valuable take-off and landing slots.

The report was put forward by the Financial Times on Monday and might have a substantial effect on the long awaited Oneworld Transatlantic alliance.

The tie up was arranged by the giant airlines to make the most of the American and European "Open Skies" agreement. The focus is primarily on routes between the US, EU, Norway, Mexico, Canada and Switzerland. Although the plan has been taken in a positive light by many, EU regulators raised concerns earlier this month that it may end up violating rules on restrictive business practices.

According to FT reports, the EU Commission is under the fear that the impending tie-up might result in "appreciable competitive harm" on the aforementioned routes. In order to make things better and get the Transatlantic tip-up through as early as possible, three of the world's top ranked international carriers have applied with the US Government for an antitrust immunity.