The National Investigation Agency (NIA) has begun a preliminary enquiry to ascertain any sabotage angle in recent train derailments and accidents, officials said on Friday.

They said at least four such cases are being looked into by the anti-terror agency officials. "A preliminary enquiry has been registered to look into sabotage angles in recent train accidents/derailments. At least four such cases are being looked into," an official said.

Nothing concrete has come up so far to suggest there were sabotage attempts in these train derailments/accidents, the official added. Some cases have been reported in the past over two months where empty gas cylinders, cement sleeper and boulders among other items were placed on railway tracks, suggesting deliberate attempts to damage railway properties and harm passengers.

On October 9, a goods train on its way to Kundanganj in Uttar Pradesh hit a cement sleeper placed on the Raebareli-Prayagraj railway section. The driver applied emergency brakes after seeing the construction part, but could not prevent the engine's cattle guard (front portion) from hitting the object.

On September 22, an empty gas cylinder was found on the track by a goods train loco pilot, who applied emergency brakes and stopped the train near Prempur Railway Station in Kanpur.

An attempt was also made to derail the Kalindi Express, heading towards Bhiwani from Prayagraj, on September 8, by placing an LPG cylinder on the track. A bottle of petrol and matchboxes were also found at the site hinting at a sabotage bid. Twenty coaches of the Sabarmati Express passenger train derailed near Govindpuri station in Kanpur after its engine hit an object placed on the track, in the wee hours of August 17.

The loco pilot of the train said that some boulder hit the cattle guard of the engine which got severely damaged and bent. There were no casualties reported in the derailment that occurred between Kanpur and Bhimsen railway stations at around 2.35 AM. Railways Minister Ashwini Vaishnaw had last month said that the railway administration was on alert against potential train sabotage bids and was holding talks with authorities including the NIA and police in several states.