NEW DELHI — Indian police released sketches today of two men suspected of planting the bombs that sparked a fire on a train to Pakistan, killing 68 people in an attack officials said was intended to disrupt the steadily improving ties between the longtime rival countries.

The two men, whose identities are not known, boarded the train when it left New Delhi on Sunday but quickly began arguing with the conductor, insisting they were on the wrong train. They were allowed to jump from the train as it slowed down about 15 minutes to 20 minutes before the crude bombs detonated, said Sharad Kumar, a senior police official.

The train goes from New Delhi to the border town of Atari without stopping, and the revelation that two were allowed off highlighted what most passengers already know — that security on the train and at stations is cursory, at best.

In further signs of lax security, Kumar told reporters that 13 passengers made it to Pakistan without passports.

"There is no security at all at the station," Ati-ur-Rahman said as he waited Monday near Dewana for word about his missing cousin who was headed for Lahore, the line's stop in Pakistan.

"There are only a few rude constables and all they're looking for is a few hundred rupees. They don't check anything," he said.

Railway Minister Lalu Prasad virtually acknowledged as much hours after the blast when he told reporters: "Though there are metal detectors, we don't have the equipment to check what is inside the luggage. We can't deny that."

Despite the attack, leaders of the rival nations said they would press ahead with their peace process. Pakistan quickly decried the attack, and Indian officials took pains to avoid laying quick blame.