A man decked in Japanese martial arts garb while wielding a sword boarded a train on Monday afternoon after jumping the fare gate at Paya Lebar MRT station.
In a Facebook post, SMRT said that it had been alerted of the incident involving the man in a "samurai outfit" at about 12.30pm and that its staff immediately informed the police.
The police said that officers who later boarded the train kept the suspect apart from other commuters "so as not to aggravate the situation" while they monitored the suspect and followed him closely when he alighted at City Hall MRT station.
The man was eventually apprehended along Victoria Street in Bugis, near Jalan Pisang, after a foot chase, eyewitnesses said. Police investigations are ongoing.
SMRT said in the post: "Passenger safety is our priority and we do not tolerate abhorrent behaviour nor allow offensive weapons to be brought on our trains."
Passengers who witness such acts should activate the Emergency Communication Button to communicate with the train captain, who will report the situation to the control centre, added SMRT.
Staff at the nearest station will render immediate assistance and alert the police and security staff.