One suspect was already detained in connection with two bomb explosions that killed 66 people and wounded at least 129 at the Pakistan-bound train in India, Icountry's railway minister said.

"On the basis of information given by eye-witnesses, one person who was present in one of the two coaches that caught fire has been detained," Railways Minister Lalu Prasad Yadav told the media, the Press Trust of India news agency reports.

The tragic blast in the Samjhauta Express Delhi-Attari train occured Panipat city, 100 kilometres north of New Delhi, late at night when most passengers were sleeping. Many of them were trapped in burning vehicles as the windows were barred. "We cannot even say whether those killed were men or women or Indian or Pakistanis as the bodies are in a bad shape. Only the post-mortem and DNA tests will tell this,' said Haryana Chief Secretary Prem Prashant.

Police found explosive devices in other vehicles, but the timers on the bombs did not go off, Haryana's Additional Director General of Police V.N. Rai said to IANS.

Pakistani and Indian survivors of the explosion are fighting for their lives at the specialized burns unit at Delhi's Safdarjung Hospital, IANS news agency reported.

"The prime minister expressed anguish and grief at the loss of lives," a spokesman for Indian Premier Manmohan Singh said, adding, "The culprits will be caught."