Two months ago Underworld reported on the curious case of an alleged terror plot against the Liberty Bell that was supposedly foiled by the FBI.

The facts of the case: on Sept. 16, five days after the devastating terrorist attacks against the U.S., a female tourist at the Liberty Bell noticed two men she thought were Arabs sitting in a white sedan across the street.

She thought they were acting suspiciously and told a park ranger, who notified the park police. The park police notified the Philadelphia police and the Philadelphia police notified the FBI.

Witnesses told City Paper that within minutes a black SUV with tinted windows pulled up and a group of FBI agents leapt out of the SUV and swarmed the car, taking two men into custody.

Phil Sheridan, Independence Park spokesman, told City Paper, "It started with a complaint from someone who saw a white Chevy Caprice driving erratically."

According to Sheridan, the park rangers asked the men in the car for ID. "The two guys had more than one identification," Sheridan explained. "They also apparently claimed they were doing something with the FBI and were going to meet them. So our folks called the FBI and turned them over to the FBI."

Sheridan also told the City Paper that the Philadelphia police bomb squad "did a bomb sweep on the car but no bombs were found."

Philadelphia police spokeswoman Maria Ibrahim also confirmed that on Sept. 16 at 12:45 p.m., the Philadelphia bomb squad was deployed and that the police and park security "detained two Middle Eastern men along with a white Chevy bearing New Jersey temp tags. The FBI were called to the location and took both men in for questioning."

When the FBI was contacted two months ago for comment, FBI spokeswoman Linda Vizi said that "there was nobody under arrest by the FBI on Sept. 16 for a plot to blow up the Liberty Bell."

Since that time the FBI has continued to insist that nothing happened on Sept.16.

But since that time, City Paper has learned that the two Arabs allegedly taken into custody on Sept. 16 were turned over to the Immigration and Naturalization Service (INS) and are still in custody -- according to a federal government source.

"It's standard procedure right now," the federal source explained to City Paper last week. "INS can hold people for immigration violations but doesn't have to make this information public. The INS holds suspects incognito while the FBI tried to put together a terror case against the suspects."

According to a federal and a local law enforcement source, not long after the two Arab men were taken into custody at the Liberty Bell, federal agents raided a convenience store in Northeast Philadelphia where one of the men allegedly worked. Two other employees were also detained by INS. The owner of the store, who is also an Arab, was reached at his home in Huntington Valley by City Paper last month and he claimed his employees had done nothing wrong.

"Already young kids vandalize my store day and night and the cops do nothing. Naming my store will do nothing but increase the attacks. I'm not going to tell the media anything at all," the owner said. "My employees did nothing wrong and the government took them away for no reason, but because they are Arab."

One federal government source claimed that at least two of the men were Egyptian and that the two men taken into custody on Sept. 16 in Philadelphia had ties to al-Qaeda and to Mohammed Atta, the leader of the Sept.11 hijackers.

Also, last week, a National Park Service source played an audiotape of a Park Service security briefing for City Paper. In the recording, the Park Service security official cites the Sept. 16 detention of two Arabs at the Liberty Bell in Philadelphia and explains that two men were terrorists with links to al-Qaeda and to Mohammed Atta. The security official also warns park service employees in Philadelphia to be alert for suspicious persons and packages in Independence Park.