No arrests have been made so far in the incident near Villupuram where suspected pro-LTTE elements blasted a railway track, police said on Sunday.
The ‘Q’ branch of Tamil Nadu police, dealing with extremist activities, was helping railway police with the investigations, highly placed officials told PTI.
Officials on condition of anonymity said “known” persons who were involved in previous such incidents and others under police scanner were being interrogated by Government Railway Police (GRP).
Directions have been issued to Railways and local police officials to intensify patrolling, they said.
Asked whether the incident would cast a security shadow on the five-day World Classical Tamil Conference at Coimbatore starting June 23, they said “all threat perceptions have been taken account” and adequate measures were in place.
Railway officials had averted a major disaster on Saturday when an alert crew of the Tiruchirapalli-Chennai Rockfort Express stopped it on noticing a gap in the tracks.
About three feet of tracks were blown off in the explosion when the train was coming towards the Perani railway station in Villupuram district in the wee hours.
Leaflets condemning the recent visit of Sri Lankan President Mahinda Rajapaksa were found at the site.