The blasts came on the eve of a visit by Foreign Minister Khurshid Kasuri, who called the attack a "horrendous act of terrorism". He said most of the victims were Pakistani nationals taking the cross-border train home. Experts said explosives were used to ignite bottles of kerosene in the train, which was carrying more than 750 people when the blasts occurred near Deewana station, 100 kilometres (60 miles) north of New Delhi.
"The intention is clear-it is an effort to destabilise peace between India and Pakistan. Innocent people have been killed," said Yadav. President Pervez Musharraf called for a full investigation by Indian authorities but vowed not to let the bloodshed undermine the peace effort between the neighbours.
"Such wanton acts of terrorism will only serve to further strengthen our resolve to attain the mutually desired objective of sustainable peace between the two countries," he said, according to a Pakistan government statement.
New Delhi Television, citing intelligence sources, said the blasts may have been linked to an attack on commuter trains in Mumbai last July that left at least 185 dead and led India to suspend peace talks for several months.
Prime Minister Manmohan Singh expressed "anguish and grief" at the loss of lives. "The culprits will be caught," he vowed in a statement. Singh later called his counterpart Shaukat Aziz and assured action against attackers. "The prime minister declared India's abhorrence for this heinous terrorist act and reaffirmed our commitment to doing everything possible to ensure that its perpetrators are punished," Singh's office said in a statement.
No group had claimed responsibility for the attack, but one suspect was detained at the site, Railways minister Yadav said. Survivors said the blasts unleashed a ball of fire. The carriages had doors for access to platforms, but not at each end. Passengers struggled to break through the barred windows and to open the doors of the moving train.
"There was a huge fire and I saw smoke coming out," said Usman Ali, who was headed back to his native Pakistan. "When I came out of the coach, I saw that the doors of one (carriage) were closed and people could not escape."
Railways Minister Sheikh Rashid said the doors of the carriages had been locked as part of security procedure. "Most of the deaths occurred because the bogies were locked from inside. Some people jumped out of train after breaking window glass," Rashid told state television from the station at Wagah, the main border crossing between the two countries.
After the blaze, 11 of 16 carriages continued the journey while five, including the two wrecked coaches-littered with burnt bangles, shoes and clothes-remained at Deewana for investigators to examine. "We now have an official count of 67 bodies recovered from the (blast) site," said Haryana state police chief Rajiv Dalal.
A dozen unexploded bottles filled with kerosene had also been recovered, and two other bombs had been defused, said JS Mahanwal, the director of the state's forensic laboratory.
He said the mix of kerosene, sulphur and nitrate believed used was different from similar attacks in the past, which had employed a plastic explosive known as RDX.
The new mix led to the fire, which charred bodies beyond recognition. "It's very difficult to say who the victims were," said Dr Ved Gupta, the head of post-mortem operations at the hospital in Panipat, five kilometres (three miles) from Deewana. Distraught and grieving relatives, meanwhile, blamed lax Indian railways security for the tragedy.
"Why couldn't the police check the bags properly at Delhi station? If they had, my sister-in-law would still have been alive," said 58-year-old Haji Nasiruddin, a businessman from New Delhi. Railways minister Yadav admitted at the site of the accident that there had been a security lapse, but said the giant state-owned rail network relied on metal detectors and did not individually check bags.
The Samjhota Express was suspended in 2002, because of tensions following an attack on India's parliament in December 2001. It was restarted in January 2004, when a new peace process was launched. Foreign capitals condemned the blasts and also urged New Delhi and Islamabad to redouble their work for peace.