India's Railway Minister said on Sunday the cause and people responsible for the country's worst train crash in decades had been identified, pointing to an electronic signal system without giving further details.

"We have identified the cause of the accident and the people responsible for it," India's Railway Minister Ashwini Vaishnaw told news agency ANI, but said it was "not appropriate" to give details before a final investigation report.

The death toll from Friday's crash near Balasore, in the eastern state of Odisha, was expected to climb above 288.

Ashwini said the "change that occurred during electronic interlocking, the accident happened due to that", a technical term referring to a complex signal system designed to stop trains colliding by arranging their movement on the tracks.

"Whoever did it, and how it happened, will be found out after proper investigation," he added.

There was confusion about the exact sequence of events but reports cited railway officials as saying that a signalling error had sent the Coromandal Express running south from Kolkata to Chennai onto a side track.

It slammed into a freight train and the wreckage derailed an express running north from India's tech hub Bengaluru to Kolkata that was also passing the site.

Odisha state's chief secretary Pradeep Jena confirmed that about 900 injured people had been hospitalised. (AFP)