Via Rail says it has increased police and canine patrols in certain train stations following what it calls an "unfounded" threat.
A spokesman for the passenger rail company says a threat was received recently and police were informed, but it appeared to be unsubstantiated.
Spokesman Malcolm Andrews says Via has nonetheless reminded employees to be vigilant and has increased patrols at some stations.
He says Via is also working closely with law enforcement.
The railway notes that passenger transportation companies around the world have been the target of unsubstantiated threats "for some time now."