BRUSSELS, Dec. 6 EU leaders expressed regret that the White House, facing opposition in the U.S. Congress, has given up efforts to open trans-Atlantic flights to competition.U.S. rules limit foreign investment in its airlines to 25 percent of the voting stock, constraining the ability of European airlines to participate in managing those airlines in which they invest. The European Union has a more liberal policy, allowing foreigners to own 49 percent of European carriers.The Bush administration, which has been pushing easing U.S. limits on foreign airline ownership, said Tuesday it was abandoning a proposed law to accomplish such an end.Mary Peters, U.S. Transportation Department secretary, said the move followed the Democrats' success in last month's congressional races.That prompted Jacques Barrot, EU transport commissioner, to express disappointment and regret at the move.Copyright 2006 by UPI