Holes were found drilled in a portion of a railway track at Kundayithodu, near Cheruvannur, on Friday.
The holes were noticed by trackmen during a routine check at the site.
No fewer than 32 holes were found on the track.
Senior Railway officials who reached the spot said it was part of an attempt to derail trains. Only by using a powerful drill could one make such holes, they said.
Police officials collected the statements of people living nearby.
“It will be quite impossible to make such holes without noise, but no one has heard any strange noises in the area,” a police officer said.
They could not determine when the holes were made. Preliminary inspection revealed that several trains had passed that way on Friday.
Railway officials said only a special inquiry would bring to light those behind the attempt. The forensic squad would conduct a detailed inspection at the site, and further investigation would be held on the basis of the squad report, they said.
Trains were passing along the route, but the track would be replaced soon, police sources said.
Meanwhile, Home Minister Ramesh Chennithala has said that the support of the State police would be extended to Railways to bring to book those who damaged the track.
