"The ATS (anti-terrorist squad) is camping there since yesterday (Saturday). As per investigations done till now, there is no concrete evidence pointing to the role of any terror outfit's involvement in it," ADG (Law and Order) Anand Kumar said.
"Chances are that the derailment may have occurred due to some other or technical reasons," the ADG said.
Cracking the whip, the Railways has sent on leave its three top officials, including a secretary-level Railway Board official, suspended four and transferred one in the wake of Utkal Express derailment near Khatauli.
The action was taken on the basis of an internal report which is learnt to have said that the rail track was found cut by a hacksaw and as a result there was a gap in the tracks, according to officials in the know.
The report also said that the fish plate and the nut bolts on a section of the tracks were not fixed properly, they said.
The train, which was on its way from Puri in Odisha to Haridwar in Uttarakhand, had 23 coaches, of which 13 derailed at Khatauli in UP, Divisional Railway Manager Delhi RN Singh said.
Six coaches of the train, which was running at a speed of over 100 kmph, were severely damaged, he added. One coach crashed into a house.
Survivors were rescued and bodies pulled were out till late on Saturday and rescue operation by the National Disaster Response Force got over at around 3am on Sunday.
Principal Secretary (Information) to the UP government Awanish Kumar Awasthi said 156 people were injured in the derailment and many among them remain critical.
More than 50 injured passengers have been discharged after medical treatment while free medical treatment of another 102 injured passengers is in progress, UP Cabinet minister Satish Mahana told PTI in Lucknow.
Railway Minister Suresh Prabhu had on Sunday morning directed Railway Board Chairman to fix responsibility on "prima facie evidence by the end of day".
"Prime facie, it seems maintenance work was being carried out on the tracks.... Some maintenance work was going on, which might have caused the derailment of Utkal Express," Member (Traffic) of the Railway Board, Mohd Jamshed said.
He said a probe would reveal if any maintenance work was being done on the tracks without permission.
It was not "clear" what kind of work was going on at the site, the official said.
(With PTI inputs)