Jerusalem District Police on Thursday night arrested a 43-year-old resident of Hebron who had crossed into Israel illegally.
Upon his arrest, near Damascus Gate, the forces searched the suspect and found him to be armed.
During a search of his body, police seized a Glock pistol loaded with a magazine.
The suspect was arrested for questioning at the Shalem police station.
He will be brought before the Jerusalem Magistrates Court on Friday for an extension of his arrest.