Shares of British Airways ( BAB) fell Thursday after the company disclosed a probe by U.S. and U.K. authorities into possible price collusion among air carriers. "The Office of Fair Trading and the United States Department of Justice are investigating alleged cartel activity involving British Airways and other airlines in relation to pricing of passenger air transportation, including fuel surcharges," the company said in a statement on its Web site. "British Airways' policy is to conduct its business in full compliance with all applicable competition laws," the company said in its statement. BA said it is assisting regulators with the investigations and has placed commercial director Martin George and communications head Iain Burns on leaves of absence during the probe. In early trading Thursday, shares of British Air lost $4.15, or 6.1%, to $63.64. Other airlines who said they are cooperating with the probe are AMR ( AMR) and Virgin Atlantic, published reports said. Bloomberg quoted Virgin spokesman Paul Charles saying: "We are aware of the investigation and are assisting with inquiries.''