The bomb, which killed 13 and injured more than 50 people, was located in express toilet. The investigators in Uttar Pradesh claim they have sufficient evidence to suspect terrorist involvement.
Traces of the high explosive RDX have been found in the compartment where the blast occurred, BBC reports.
Though forensic experts are yet to complete their investigations into Thursday's blast in Jaunpur district on the super fast Delhi-bound Shramjeevi Express from Patna, police officials involved in rescue and relief operations said RDX, a lethal explosive mostly used by terrorists, could have been used.
"The blast was definitely quite a powerful one as it ripped apart the floor and damaged the ceiling of the toilet where it was apparently hidden," a local police official from Jaunpur told IANS over the phone.
Director General of Police Yashpal Singh said on Friday that he would not comment until the forensic team completed its probe. However, officials on the spot said there were striking similarities between Thursday's incident and the August 2000 blast on the Sabarmati Express near Ayodhya that left 12 dead.
In the case of the Sabarmati Express, the use of RDX was clearly established. Railway Minister Lalu Prasad rushed to Jaunpur on Thursday night and Uttar Pradesh Chief Minister Mulayam Singh Yadav followed on Friday. However, none was willing to confirm a terrorist hand behind the incident.
"We cannot say whether it was a bomb or just some passenger illegally carrying some explosives," Lalu Prasad was quoted as saying by Hindustan.
According to Reuters, New Delhi blamed Muslim militants backed by Pakistan's spy agency for the blast.
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