The Pakistani government condemned the India-Pakistan train explosion Monday as an "act of terrorism," and said it expected India to carry out of a full investigation.
The explosion occurred on a train headed for Pakistan and set off a fire that swept through two coaches, killing at least 65 people. Dozens more people were injured.
Indian officials initially stated the attack was aimed at undermining the peace process between India and Pakistan.
Authorities said that two suitcases packed with unexploded crude bombs and bottles of gasoline were found in train cars not hit in the attack, leading them to believe the fire was set off by an identical explosive device.
"This is an act of sabotage," Railway Minister Laloo Prasad told reporters in Patna, India. "This is an attempt to derail the improving relationship between India and Pakistan."
Initial reports indicated that most of the scores of people killed in a fire on the train triggered by the explosion were Pakistanis, Pakistani Foreign Ministry spokeswoman Tasnim Aslam said.
"We expect the Indian authorities to conduct a full investigation and punish those responsible for this heinous act of terrorism," Aslam said.
India's junior home minister, Sriprakash Jaiswal, called the attack part of a "conspiracy ... to disturb communal harmony, India's stability and to disturb the peace process between India and Pakistan."
He said the homemade bombs were intended to start a fire on the train one day before Pakistani Foreign Minister Khursheed Kasuri was to arrive in New Delhi for talks on the ongoing peace process.
The train fire broke out just before the train reached the station in the village of Dewana, about 80 kilometers north of New Delhi. The train was traveling from New Delhi to Atari, the last railroad station before the border with Pakistan. At Atari, passengers change trains in a special station, switching to a Pakistani train that takes them to the Pakistani city of Lahore.