DEWANA, India - An explosion on a train headed for Pakistan set off a fire that swept through two cars and killed at least 66 people in an attack that a government minister said was aimed at undermining the peace process between India and Pakistan. 

A Thar Express train on the route from Monabao at the Zero-Point Station of Indo-Pakistan border. At least 53 people burned to death after a suspected blast aboard a train travelling from India to Pakistan. [AFP]

Authorities said two suitcases packed with unexploded crude bombs and bottles of gasoline were found in cars not hit in the attack, leading them to suspect 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."

Prime Minister Manmohan Singh expressed anguish and grief at the loss of lives and said that "the culprits will be caught," a brief statement by his office said.

India's junior home Minster, Sriprakash Jaiswal, said the homemade bombs were not powerful, and were simply 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.

Pakistani Foreign Ministry spokeswoman Tasnim Aslam said there were "all kinds of terrorists" who may have been behind the attack but said it was too early to speculate about the possible motive.

"We expect the Indian authorities to conduct a full investigation and punish those responsible for this heinous act of terrorism," she said.

Frantic relatives flocked to New Delhi's main railway station Monday morning in search of answers. But there was only a handwritten list, posted on a bulletin board, with the names of 13 injured people and one identified body.

Mohammed Wasim Khan, who had dropped off his uncle and two young nephews at the station late Sunday, said railway officials had brusquely told him to take a train to the scene of the blast if he wanted more information.

"What am I going to tell my cousins?" he said, crying. "What will I tell them?

The fire engulfed two cars of the Samjhauta Express, one of two train links between India and Pakistan. Because of security concerns, the train is kept sealed ¡ª with locked doors and barred windows in the lower-class coaches ¡ª from New Delhi to the border. Passengers may have been trapped inside the burning cars.

The explosion and fire struck just before the train reached the station in the village of Dewana, about 50 miles north of New Delhi.

People who live near the tracks rushed to the train with buckets of water soon after the fire broke out. The blaze was eventually extinguished after fire trucks arrived.

Speaking to reporters at the scene, Bharti Arora, superintendent of the Haryana state railway police, said the death toll had risen to 66.

At least 30 passengers who were burned or injured in the blaze have been hospitalized in the nearby town of Panipat, the general manager of the Northern Railway, V.N. Mathur, told reporters.

The dead included both Indians and Pakistanis, officials said.

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.

Within hours of the fire, authorities detached the burned cars and the rest of the train left for the India-Pakistan border.

The train links are one of the most visible results of the peace process under way between nuclear-armed rivals India and Pakistan, and one of the easiest ways to travel across the heavily militarized border.

Relations between the two countries have warmed in recent years, though they nearly went to war following a 2001 attack on the Indian Parliament that India blamed on Pakistan. The two now hold talks regularly.

The enmity between India and Pakistan centers on Kashmir, a largely Muslim Himalayan region divided between the two countries but claimed in its entirety by both.

More than a dozen militant groups -- most based in Pakistan -- have been fighting in Indian Kashmir for nearly two decades, seeking independence for the region or its merger with predominantly Islamic Pakistan. More than 68,000 people, most of them civilians, have died in the violence.

Monday's blaze revived memories of the train bombings on Mumbai's commuter rail lines last July that killed more than 200 people.

Police say Lashkar-e-Tayyaba, or Army of the Pure, a Pakistan-based Islamic militant group, as well as the Students' Islamic Movement of India, or SIMI, a banned group based in northern India, were behind those blasts. Officials also have alleged that Pakistani intelligence was involved in the attacks, but Pakistan repeatedly has denied the accusation.

In 2002, Hindu-Muslim riots broke out after a train fire killed 60 Hindus returning from a religious pilgrimage. Muslims were blamed for the fire in the western state of Gujarat, and more than 1,000 people, most of them Muslim, were killed by Hindu mobs.

About 84 percent of India's more than 1 billion people are Hindu, and Muslims account for about 14 percent.