The first train, packed with morning commuters, had come to a halt in a tunnel after developing engine trouble, YTN TV said.

A second following train had discharged its passengers at a station and was then sent to help shunt the stranded train to safety, but instead slammed into its back at speed as it rounded a corner.

The force of the impact derailed the stalled train whose passengers were violently pitched forward, resulting in numerous injuries, including bone fractures, the report said.