More than 66 people, including many Pakistani nationals, have been killed in a fire aboard the only train linking India's capital with the Pakistani border. Indian authorities say the fire, which also injured as many as 50 passengers, was an act of sabotage meant to undermine relations between the two countries. Meanwhile, the United States has described the bomb attack as a 'deliberate act of terrorism.' A statement from the American embassy in New Delhi said the U.S. government is shocked and deeply saddened by the loss of life in the bombing.

VOA's Steve Herman reports from New Delhi.

A policeman investigates inside one of the burnt compartments of Samjhauta Express after fire raked through it as it was traveling to Pakistan, at Deewana village in India, 19 Feb 2007

Passengers say two separate blasts tore through cars on the express train just about midnight. It had left New Delhi about an hour earlier and was headed to the border with Pakistan.

Some government ministers and police are calling this a terrorist attack meant to derail the peace process between New Delhi and Islamabad. Indian Railway Minister Laloo Prasad Yadav is among those expressing such a view.

Yadav says innocent passengers on the train were deliberately targeted to harm India-Pakistan relations.

Northern Railways general manager V.N. Mathur says clear evidence has been found of sabotage.

The railway official says two bombs, which failed to detonate, were found inside suitcases in another carriage of the train.

Passengers in the coaches that caught fire had difficulty escaping. The Samjhauta Express is a high security train with locked doors and bars on the windows of the lower class carriages.

 Most of the bodies were burned beyond recognition. Some of the most critically injured survivors have been brought to a hospital in New Delhi, about 80 kilometers to the south.

One injured survivor told reporters her five children died in the burning carriages.

The express is known as the "Train of Peace" and is one of the most convenient ways to cross the heavily militarized India-Pakistan border.

The two countries have spent the past few years trying to improve their historically tense relationship. One of the biggest issues causing friction is Kashmir - a region with a largely Muslim population that is divided between the two countries.

Muslim separatists have fought an insurgency for more than a decade in Indian-controlled Kashmir, and New Delhi has accused Pakistan of aiding the militants. The government in Islamabad denies the allegation.

No one has claimed responsibility for the train fire, which occurred a day before Pakistan's foreign minister Khurshid Kasuri is to visit India to discuss joint anti-terrorism measures.

Indian Prime Minister Manmohan Singh, expressing "grief and anger", has vowed that those responsible for the attack will be caught.

In recent years India has seen several attacks on its heavily used railway system. Last July, more than 200 people died in a series of coordinated bombs that went off on Mumbai trains during rush hour.