A Bihar court on Wednesday sent three persons arrested in connection with the Indore-Patna Express train derailment to six-day police custody, the state police said.

The District and Sessions court at Motihari, the district headquarters of East Champaran, sent to police custody the three alleged hard-core criminals -- Moti Paswan, Umashankar Prasad and Mukesh Yadav -- who were arrested from Ghorasahan area on Tuesday.

"The National Investigation Agency (NIA) and Anti-Terrorist Squad (ATS) will interrogate them," a police official said.

East Champaran Superintendent of Police Jitendra Rana said Paswan confessed during interrogation that Pakistan's Inter-Services Intelligence (ISI) had planned the derailment.

Rana said the police also found evidence to link the three to the ISI.

"Paswan said he was involved in the derailment, along with some others, including Zubair and Ziaul, who were arrested in Delhi."

"Paswan has already identified the two persons arrested in Delhi," Rana added.

The police officer said three persons were arrested from Nepal in the case.

"We have been informed by Nepal Police that the ISI had hired Brajkishore Giri -- one of the three criminals arrested there -- to execute terror activities in India," he said.

The ISI has been using Nepal as a base to implement its terror actions through Bihar by using hired criminals, Rana added.

An earlier report from Delhi said an NIA team had reached Motihari district on Wednesday to investigate the role of ISI in the train's derailment near Kanpur in Uttar Pradesh.

In the early hours of November 20, 14 coaches of the Indore-Patna Express derailed near Pukhrayan station, about 60 km from Kanpur city. At least 120 persons were killed and around 100 others injured.