Robbers cut through the roof a train coach in Tamil Nadu and escaped with cash belonging to the Reserve Bank of India (RBI), police said.
The audacious robbery came to light when the Salem Express reached Chennai from Salem in the state.
According to officials, the RBI booked a coach in the train.
The bank had reportedly loaded 228 trunks with currency, estimated at around Rs.340 crore. But some officials said they were all soiled notes.
It is not know how much cash was robbed.
The robbers seem to have entered the coach after cutting through the roof sometime during Monday night or early on Tuesday when the train reached Virudhachalam.
Another theory is that the robbery could have happened soon after the train left Salem and before it reached Virudhachalam as the route was non-electrified route. On the other hand, the route between Virudhachalam and Chennai is electrified.