(Adds details, byline) By Prithwish Ganguly NEW DELHI, Feb 22 (Reuters) - The hunt for the bombers of a train from India to Pakistan spread to several north Indian states on Thursday as investigators said they were pursuing new clues and had detained six people for questioning. The Sunday midnight blasts on the Samjhauta Express -- which connects New Delhi to the Pakistani city of Lahore -- sparked a fire which killed 68 people about an hour after the train had left the Indian capital. Although no group has admitted responsibility, New Delhi suspects the attack was the work of Muslim extremists opposed to a peace process between India and Pakistan. While two bombs placed in suitcases exploded on two coaches of the train, two others failed to go off and investigators have been pursuing leads offered by them. "We have formed some teams to go to Uttar Pradesh, Rajasthan, Delhi and Punjab," said R.C. Mishra, a top police officer in Haryana state, where the attack took place, referring to neighbouring states. "We have some specific information but have to wait for the investigation process to get over," he said, adding that police were also verifying passengers' passports. CLUE IN NEWSPAPER? Three of nine people detained for questioning had been released and the rest were being probed further, another Haryana police officer, who did not want to be identified, said. A Pakistani national, Usman Mohammed, who had thrown one of the suitcase bombs off the train and had been held for questioning, was cleared of suspicion and released to the Pakistani mission in New Delhi, he said. Separately, investigators in New Delhi said a Hindi newspaper wrapped around explosives in one of the defused bombs was an edition published from Aligarh, a town with a large Muslim population in Uttar Pradesh. "This may give some clues to police to carry forward their investigation," a senior officer told Reuters. Delhi police said on Wednesday they were investigating a suspicious phone call made to Pakistani Kashmir just after the bombs exploded, indicating the possibility of a Kashmiri separatist hand in the attack. But militant groups have strongly denied any role, instead blaming Indian agencies and hardline Hindu groups. India and Pakistan have said they would not allow the attack to undermine their peace process, and New Delhi has agreed to share information from the investigation through a joint panel formed last year to fight terrorism. The Indian foreign ministry said 27 of the 68 bodies had been identified as that of Pakistani passengers and 21 of them had been handed over to Islamabad. Some among the injured Pakistani nationals who were being treated at a New Delhi hospital were also being taken home by a Pakistani Air Force plane. (Additional reporting by Palash Kumar in New Delhi and Geetinder Garewal in Chandigarh)
