In a nondescript building near the junction of Interstates 70 and 270 in Bridgeton, Mo., just outside of St. Louis, lies what appears to be the heart of AT&T’s secret network surveillance on behalf of the U.S. government, former employees of the company said.

Salon reports that in 2002, AT&T converted part of the facility into a highly secure area complete with a “mantrap,” an enclosed space with separate doors on entry and exit requiring retinal scan and fingerprint authentication to pass through, and obtained Top Secret/Sensitive Compartmented Intelligence security clearance for several employees, the former employees said. The security is consistent with work on an NSA program, according to intelligence sources who spoke with Salon.

The former employees said that they were told the employees in the secret room were “monitoring network traffic” and the project was for “a government agency.”

“It was very hush-hush,” said one of the former AT&T workers. “We were told there was going to be some government personnel working in that room. We were told, ‘Do not try to speak to them. Do not hamper their work. Do not impede anything that they’re doing.’”

The importance of the Bridgeton facility is its role in managing the “common backbone” for all of AT&T’s Internet operations. According to one of the former workers, Bridgeton serves as the technical command center from which the company manages all the routers and circuits carrying the company’s domestic and international Internet traffic. Therefore, Bridgeton could be instrumental for conducting surveillance or collecting data.

If the NSA is using the secret room, it would appear to bolster recent allegations that the agency has been conducting broad and possibly illegal domestic surveillance and data collection operations authorized by the Bush administration after the terrorist attacks of Sept. 11, 2001. AT&T’s Bridgeton location would give the NSA potential access to an enormous amount of Internet data — currently, the telecom giant controls approximately one-third of all bandwidth carrying Internet traffic to homes and businesses across the United States. — Salon News

But Russell Tice, who’s still alive and kicking, says you can bet your banana there’s something going on in there. He said that the security measures point to “something going on that’s very important, because you’re talking about an awful lot of money.” He also said that the arduous six-month clearance process the AT&T employees went through to gain access to that facility is indicative of NSA involvement. The background checks were extensive, involving reviews of past employment, school records, and interviewing people they knew as far back as elementary school.

The former AT&T employees were not able to say whether telephone calls or Internet traffic was being monitored from the Bridgeton facility, though prior to its conversion the 20 foot by 40 foot secret room was used by AT&T’s WorldNet Internet backbone.

AT&T, for their part, refuses to confirm or deny anything. The government also refused to confirm or deny “actual or alleged operationial issues.”

The Electronic Frontier Foundation has filed a lawsuit against AT&T alleging that the company illegally provided intercepts of telephone and Internet traffic to the NSA under the terrorist surveillance program which, while being authorized by President Bush, the EFF says is not actually lawful. The U.S. has asserted the state secrets privilege in the lawsuit, and the court will hear oral arguments on that motion Friday.

EFF’s lawsuit focuses on a similar, but less secure, AT&T secret facility in San Francisco, which appears to take orders from the Bridgeton facility. It’s not yet clear whether the new revelations about the secret room in Bridgeton will have an impact on the court case.

In May, Wired News published documents it received from Mark Klein, a former AT&T employee and witness for EFF in the AT&T case, showing details of the San Francisco secret room and some of the equipment being used in the room.