MEMPHIS, Tenn. -- Not content with mere security guards, FedEx has created its own private police force.

The 10 officers don't wear uniforms, but they can carry guns and have full law enforcement powers to protect the world's largest cargo airline from terrorism or other threats.

"They primarily function in sort of a detective mode," said Kristin Krause, spokeswoman for the Memphis-based package delivery company. "They also have a heavy concentration on executive security."

But the private police force has critics, including David Webb, chairman of the FedEx unit of the Air Line Pilots Association, who says there isn't enough public oversight.

"Who gets to make the accusations and give the instructions to these law enforcement officers to engage in an investigation?" Webb said.

"What level of due process and probable cause has been met and who, more importantly, is going to be evaluating whether that's an appropriate level of due process or probable cause?"

Like most large corporations, FedEx has long had an extensive security force to guard its property and personnel.

But two years ago, FedEx won approval from the state legislature to take its security up a notch and organize a police force of commissioned law enforcement officers.

With little debate, state lawmakers amended a statute authorizing a police force for the Tennessee Valley Authority, so it would include airlines headquartered in Tennessee, which means FedEx.

Krause said the FedEx police can launch any investigations they feel are necessary. But once the officers think they're on to something, they notify traditional law enforcement agencies, she said.

"It's just an additional layer of security for us," she said.

FedEx refused to let any of its officers be interviewed.

FedEx is not the first company to have its own police force. Railroads have had private police forces since the 1800s, and some private colleges currently have such officers, said Gene Voegtlin, legislative council for the International Association of Chiefs of Police.

"It's all a question of standards and training, and as long as they meet the standards that are in place, there shouldn't be a real problem," he said.

But FedEx's main competitor, Atlanta-based United Parcel Service, will continue to rely on its security guards and use traditional law enforcement for police work, said spokesman Bob Godlewski.

"They do that for a living," he said.

Since the FedEx police force is made up of commissioned officers, it gets a seat on a regional terrorism task force run by the FBI.

The task force, one of 66 around the country, meets twice a month to review intelligence on terrorist activities from around the world. FedEx is the only private company on the Memphis regional task force.

"As the largest cargo carrier in the world, they have a lot of issues that impact them that we might be interested in. That's about as far as I can go with that," said Matt Chapman, the FBI agent in charge of the Memphis task force.

Task force members cannot discuss the group's work with anyone lacking security clearance, including corporate officers at FedEx.

"They don't have to share or pass that information because they're the decision makers," Chapman said. "They can just take action."

The officers are commissioned by the state Department of Public Safety and must have the same training as any other officer in Tennessee. But they are supervised by FedEx, not by any state agency, said Mark Bracy, director of the Tennessee Law Enforcement Training Academy.

"(FedEx) would be liable for any of their acts," Bracy said.

But that's part of the problem, says Barbara Kritchevsky, a University of Memphis law professor who compared the FedEx police force to the privately operated prisons that are springing up around the country.

"You have private companies sort of controlling aspects of government. ... You have a concern about what sort of controls there are," she said.