Washington: American Airlines and British Airways won tentative US government permission to deepen their trans-Atlantic alliance as they counter competition created by the 2008 lifting of flight restrictions between the US and Europe.

American Airlines, the second-largest US carrier, and British Airways, Europe's third-biggest, may jointly price, market and schedule international flights in their Oneworld alliance without fear of antitrust prosecution, the US Transportation Department said.

As a condition of approval, American and British Airways must yield four pairs of takeoff and landing slots at London's Heathrow Airport, Europe's busiest, to rivals that would provide new US service, the Transportation Department said. That's a fourth of the 16 pairs of slots the department asked the carriers to give up in 2002, when an earlier request for antitrust immunity fell through.