New Delhi: Sniffing a major scam of at least Rs 4,000 crore in the railways, CBI is likely to file a case soon into alleged under-reporting of the actual weight of loaded goods wagons through the manipulation of software by officials.

CBI sources said that in the financial year 2012-13, railways transported 1,008 million metric tonnes of freight and earned Rs 85,262 crore through it, which constituted 67 per cent of the total revenue for the period.

The goods are required to be weighed at the originating station or en route or at the destination point with a view to plugging the leakage of revenue and to avoid over-loading of the wagons, the sources said.

An official in CBI said inputs were received that this system has been manipulated at several places in such a way that over-loading is concealed and weight of the wagon is shown to be within the permissible limit.

"Highly sophisticated methodology of crime by manipulating the software of the system is suspected," the official said.

The sources said it is further suspected that the alleged manipulation has been done through collusion amongst railway officials, private vendors and freight operators.

"Even a 5 per cent under-reporting of actual weight of freight leads to a difference of Rs 4,263 crore by 2012-13 figures. It is not only causing huge financial loss to the exchequer but also (bringing) corresponding gain to private freight operators and is damaging railway tracks and wagons, thus adversely affecting railway safety," an official said.

Railways had in consultation with Research Development and Standards Organisation (RDSO) installed 200 'Electronic In-Motion Weigh Bridges' at various locations across the country to weigh the freight in transit.

Six vendors have been roped in by RDSO for setting up the bridges, which automatically measure the weight of goods train wagons passing through them at a speed of 15-km per hour, CBI sources said.