The cross-border rail line between Dublin and Belfast remains closed today as a security operation continues in Newry.
Northern security officers are still trying to locate the source of two explosions heard in the Newry area early on Saturday.
Thousands of passengers, many of them French rugby fans in Ireland for last Saturday's Six Nations international were transferred over the border by bus.
The alert is expected to continue until Wednesday at least, as 40 miles of track are being inspected.