High-speed diesel worth Rs 22 lakh has been found pilfered from a rail wagon with armed guards that travelled around 1,400km from Assam to reach Budge Budge on the city’s southern fringes last week.

Police said eight of the 40-odd tanks of the wagon were found empty with no sign of leakage, suggesting that the security seals had been tampered with.

The wagon was guarded by the Railway Protection Force (RPF) throughout its journey from Numaligarh Refinery in Assam’s Golaghat district to Budge Budge via Rampurhat, New Jalpaiguri and Burdwan. The train also touched Nagaland and Bihar along the way.

“The train covered a long distance and we do not know yet where the pilferage took place,” Asit Pal, the deputy commissioner of the police’s port division, told Metro.

The railways would have to compensate Bharat Petroleum if it is proved that the oil was pilfered, an official said.

Militants in the Northeast are usually blamed for any instance of theft from rail wagons originating there, but Maoists in Bengal have also come into the equation this time. “We suspect the pilferage was the handiwork of either Naga rebels or Maoists in Bengal,” said an officer of West Port police station, where the FIR was lodged.

This is not the first time oil has been pilfered from a rail wagon coming to Budge Budge from Assam.

In August last year, oil worth around Rs 18 lakh was stolen from six tanks that were part of a wagon coming to the city. Sleuths blamed it on a militant operation in a forest in the Karbi Anglong district of Assam.

“The case was later handed over to Assam police but the mystery of the missing oil hasn’t been solved yet,” an officer said.

A rail wagon built to transport petroleum products comprises 40 to 45 tanks, carrying anything between 18,000 and 48,000 litres.