The FBI is investigating an infrared device found next to train tracks in Philadelphia, amid reports of suspicious surveillance of trains in New Jersey: Device found by tracks. (Hat tip: Colt.)

The FBI is investigating the discovery of an electronic device found alongside SEPTA train tracks in West Philadelphia, but the agency yesterday stressed that there was no evidence to suggest it was linked to terrorism.

News reports of recent unauthorized surveillance of NJ Transit trains and SEPTA’s discovery of the electronic device prompted officials to issue assurances that such law enforcement attention has become commonplace.

The FBI is trying to discern the purpose of a black remote transmitter - about the size of a baseball - that was spotted by a SEPTA conductor May 5, SEPTA spokesman Richard Maloney said. The conductor removed the object from the Powelton yard, and SEPTA police turned it over to the FBI on May 12, he added.

“It was a simple motion detector. We don’t know who put it there or why it was there,” FBI spokeswoman Jerri Williams said yesterday.

In a joint statement, the FBI and SEPTA said: “There is no evidence to indicate that this device has any nexus to terrorism.”