The group of major airline companies currently building an online travel service said Friday they would cooperate with federal regulators now investigating the venture.

The Justice Department (DOJ) has launched a probe into whether the five companies involved in the project have established proper safeguards to ensure the site does not violate federal antitrust laws, according to reports. A DOJ spokeswoman Friday confirmed that an investigation was ongoing but declined to give any further details. In a joint statement, the consortium--Continental Airlines, UAL's United Airlines, Delta Air Lines, Northwest Airlines and AMR's American Airlines--said they are confident that the site, dubbed T2, meets all antitrust requirements, saying it will benefit consumers by offering them an abundance of travel information and more choices. The DOJ probe follows a formal request in February by U.S. travel agents asking the government to review the Internet travel service, saying it would violate antitrust laws. Traditional travel agents have been squeezed as airlines slash commissions, aggressively sell tickets through their corporate Web sites and partner with existing online travel sites. The airlines' site, which is scheduled to be running by the middle of the year, will allow customers to book flight tickets, hotel rooms, car rentals and tours. It will compete with similar services such as Expedia and Travelocity.com and be independently managed and operated, the companies said. In a complaint filed with the DOJ in February, the American Society of Travel Agents (ASTA) charged that the service would use its members less and would lead to price fixing.