"The Commissioner Railway Safety, southern zone, S K Mittal will conduct an inquiry into the cause of the accident and submit the report at the earliest," railway ministry spokesperson Anil Kumar Saxena said in New Delhi.

He said prima facie the cause of the accident seems to be overlooking of the signal and non-adherence of the speed restriction.

The Chennai Beach-Vellore Cantonment Mainline Electrical Multiple Unit train rammed into the Arakkonam-Katpadi passenger from behind as it was waiting for a signal at Sitheri Station, about 90 km from Chennai, around 9.40 pm on Tuesday night.

About the toll, he said ten persons have been killed and 72 persons injured in the accident out of which 25 were grievously injured.

Asked about the disruption in rail traffic, he said, "Work is going on a war footing to clear the tracks and the up-line is expected to be operational by 2 pm and the down-line in the Banglaore-Chennai section by 6 pm.

This is the third major accident in two months.

On July 10, 70 people were killed when the Howrah-Kalka Mail derailed near Kanpur and three weeks later some coaches of Guwahati-Bangalore Express derailed in West Bengal's Malda district and were hit by another train leaving three dead.