Gardaí made the arrest after reports of a man on a train carrying a firearm.
Officers were alerted to the incident on a train near Templemore station in County Tipperary at around 6:50am on Friday morning.
Armed Gardai support local and civilian units at the scene.
A garda spokeswoman said: “A male was identified on the train. He was searched by gardai and found to be in possession of what is believed to be an imitation firearm, subject to a technical examination,” reports Breaking News.
The 20-year-old was arrested at the scene and is currently being held at Tipperary Garda Station under Section 30 of the Offenses Against the State Act 1939, reports Breaking News.
The investigation is ongoing.
Tell us your thoughts in the Facebook post and share this with your friends.