The West Bengal government on Monday turned down the Centre's offer to have last week's Jhargram train mishap investigated by the CBI, saying the state police had covered considerable ground in the case.
Railway Minister Mamata Banerjee wanted a probe by the Central Bureau of Investigation on Friday, when 148 lives were lost in the tragedy.
State Home Secretary Samar Ghosh said: "We have replied to the (Centre's) letter stating there is no requirement to hand over the investigation to the CBI as the Criminal Investigation Department (CID) has already made substantial progress in the case."
This is the first train accident being probed by the CID, an arm of the state police.
Meanwhile, Union Home Minister P Chidambaram has agreed with the West Bengal government that it was the handiwork of the Maoists.
Chidambaram said: "The needle of suspicion in the attack on the Gyaneshwari Express in West Bengal points to the Maoists or their front organisation." He had said within hours of the incident that it was an act of "sabotage" but had not named the Maoists.
This home minister's position is not in step with the one taken by Banerjee, who said she would wait for the probe to be completed before laying the blame at the door of the Maoists.
For the past one year, ever since Maoist trouble spilled over to West Bengal from neighbouring states, Banerjee and her party, the Trinamool, had been ambivalent on the question of violence by the red brigade.
Ghosh said a letter reached Chief Secretary Ardhendu Sen on Sunday, seeking the permission of the state to hand over the investigation to the CBI.
The Gyaneshwari Express, bound for Mumbai, ran into the death trap at 1:25 am on Friday at a point 134 km to the west of Kolkata. The tragedy took place after 13 bogies of the train jumped rails because fish plates and portions of the track were removed. A goods train from the opposite direction ploughed through four displaced bogies.
When asked why the CID was probing a rail accident case, Ghosh said, "The Commissioner of Railway Safety and Security will only examine the cause of the accident and not anything beyond it. But in this case criminal action is involved and the area is a Maoist-dominated zone. The CID has started investigating what caused the derailment beyond the technicalities."