SARDIHA The police were searching on Saturday for Maoist rebels believed to be responsible for a crash involving a crowded passenger train, as rescuers continued pulling bodies from the wreckage.
The train derailed and smashed into an oncoming goods train on Friday, killing 114 people and injuring at least 200. The death toll is expected to rise.
"We have identified the people who are behind the incident. These are Maoists and we are trying to trace them and bring them to justice," said Manoj Verma, a senior police official.
The crash site in West Bengal state is in a Maoist stronghold and police said some 150 rebels had been camping in the crash area for the past few days.
Railway officials said there would be no passenger trains at night in some of the Maoist-hit areas of eastern India for the next few days in view of Friday's attack.
Prime Minister Manmohan Singh has described the Maoist insurgency as India's biggest internal security challenge.
Maoists, who say they are fighting for the rights of the poor and landless and want to overthrow the government, have stepped up their attacks in recent months. More than 1,000 attacks were recorded in 2009 and 600 people were killed.
The Maoists number some 20,000 combatants, with 6,000-8,000 hardcore fighters, and regularly attack railway lines and factories, aiming to cripple economic activity.
The rebels control vast swathes of mineral-rich areas, and the government has often struggled to transport coal to power and steel firms. The rebels extort about $300 million from companies in the country every year to fund their movement.
The latest attack will put further pressure on the Congress party-led government to bring in the military to tackle the four-decade insurgency across eastern and central India.
Rescuers continued to prise open mangled train coaches on Saturday to remove more bodies from the wreckage.
"The toll has gone up to 114 and we are expecting more bodies," said Soumitra Majumdar, a railway spokesman.
The cause of the derailment remains unclear. Some railway officials initially said a bomb had derailed the passenger train, but police said they were also looking at other possible sabotage methods, such as the removal of track "fish plates".
Railway officials will begin their investigation into the crash on Monday after all the bodies have been recovered.
The Maoists started their campaign in 1967 armed with bows and arrows and stolen rifles, but the government says they now buy high-powered weapons from Chinese smugglers and are in touch with other militant groups in India.
(Additional reporting by Bappa Majumdar in NEW DELHI; Writing by Devidutta Tripathy, editing by Tim Pearce)