Pakistani President Gen. Pervez Musharraf said Monday's deadly attack on a train heading through India to Pakistan must not disrupt the peace process between the South Asian rivals. Musharraf condemned the explosion and fire that killed scores of people on the New Delhi-Lahore service as an act of terrorism, and said it would only stiffen resolve to pursue the process. "The president underscored the need for the leadership of Pakistan and India to move forward undeterred in the quest for dispute resolution and lasting peace in the region," a government statement said. "He said that we will not allow elements which want to sabotage the ongoing peace process (to) succeed in their nefarious designs," it said. Foreign Minister Khursheed Kasuri said he will go ahead with a planned visit to India on Tuesday, the state-run Associated Press of Pakistan reported. Officials in Islamabad said there were 553 Pakistanis among the 757 passengers on board the Samjhauta Express, one of two train links set up between the neighboring countries under the three-year-old peace process. Foreign Ministry spokeswoman Tasnim Aslam said that initial reports indicated that most of those who died were Pakistanis. India was solely responsible for the security of the train on its side of the border, she noted. "We expect the Indian authorities to conduct a full investigation and punish those responsible for this heinous act of terrorism," Aslam said. She said there were "all kinds of terrorists" who may have been behind the attack, but that it was too early to speculate about the possible motive. Pakistani Railway Minister Sheikh Rashid Ahmed said officials knew of no threats against the twice-weekly train service and that it would continue. A train left Lahore on Monday morning for the Indian town of Atari to pick up those who had been able to continue their journey after the attack, he said.