BANGOR — An 18-year-old charged with having homemade explosive devices that he intended to use to attack a mosque and other houses of worship in Chicago pleaded not guilty to federal charges.

Xavier Pelkey, of Waterville, was arraigned Thursday after being indicted on a charge of possession of unregistered destructive devices. He remained in federal custody pending trial.

Pelkey was arrested Feb. 11 by FBI agents who allegedly found three homemade explosives. The devices were made of fireworks bundled together with staples, pins and thumb tacks to create shrapnel, the FBI said.

He was allegedly was in communication with two juveniles about his plans to travel to Chicago to attack a mosque, and possibly a synagogue, prosecutors have said.

Pelkey’s attorney didn’t return a call Friday seeking comment.