The Commissioner of Railway Safety (CRS) Southern Region, who carried out the probe, also recommended switching off power points provided for charging laptops and mobile phones in AC coaches between 10 pm and 6 am.
"The December 28 accident was most probably caused by advertent act or by an act of negligence on the part of unidentified passenger(s) or person(s)," said Satish Kumar Mittal, CRS Southern Region in his provisional findings.
As per the post-mortem report, the cause for the death of majority of passengers was given as gaseous asphyxia with 100 per cent burns and neurological shock, the findings released to the media said.
The CRS said burnt and melted adopter and burnt laptop were found on Berth no 13 and also burnt cells in the ill-fated coach.
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According to the findings, all protective devices -- high rupture capacity (HRC) fuses, moulded case circuit breakers (MCCB), miniature circuit breakers (MCB) and electric circuits were found intact in the coach except 40 amp MCBs and smaller MCBs for supply to light, fan and mobile charger circuits which were in burnt condition.
In other "immediate recommendations", CRS said in order to reduce combustible materials to some extent, Railways should do away with curtains in gangway portions of AC coaches.