The Indian railways authorities have not ruled out the possibility that sabotage or human error led to the train accident at Sainthia in West Bengal's Birbhum district on Monday, in which 60 people were killed and some 90 others were injured.

The deadly incident took place when the Sealdah-bound Uttar Banga Express rammed into the stationary Bhagalpur-Ranchi Vananchal Express from the rear at Sainthia station, some 191 km from Kolkota, the capital of the eastern Indian state.

Railway officials said they cannot rule out sabotage or tampering of signals, as the tracks at the accident site have an " absolute block signals system." This system allows only one train between two signals. The signal system could have been tampered with, or the Uttar Banga Express driver jumped it.

"Nothing can be ruled out. It may be possible that our equipment might have been tampered with. It will be known only after inquiry," Eastern Railways General Manager V. N. Tripathy told reporters here.

"The Commissioner of Railway Safety is holding an inquiry after which we will be able to know what exactly happened," he said.

To another question, he said that the Uttarbanga Express, which rammed into the rear of Vananchal Express, seemed to be running at a much higher speed than it was supposed to while entering the Sainthia station.

"What caused the accident is a mystery to us. The driver of the Uttarbanga Express was a very good driver. He had stopped the train properly at previous station. We are puzzled," the Eastern Railways general manager said.

Tripathy said all bodies had been pulled out from the compartments. "There is no one in any of the affected coaches. We have checked them," he said.

A team of National Disaster Relief Force is at the site with sniffer dogs to trace anyone who was still trapped.

Altogether 167 army men and officers arrived with doctors and para-medical staff from nearby Panagarh and Kanchrapara Army stations.

The engine of the Uttarbanga express was totally damaged after it rammed into the rear of the Vananchal Express in Sainthia station in Birbhum district. The luggage van of the Vananchal Express split into two and lay beside the track.