A fracture in the rail line was responsible for the Howrah-Kalka Mail accident that claimed 70 lives last month, the preliminary report submitted to Railway Ministry, claimed.
Amid concerns over increasing number of train accidents, Prime Minister Manmohan Singh has sought a detailed safety plan from the railways.
The toll in Sunday's derailment in Fatehpur, Uttar Pradesh went up to 53 with 15 more bodies, including that of a Swedish national, being recovered from the mangled compartments of the ill-fated Delhi-bound Kalka Mail.
A dense blanket of fog enveloped the entire North India affecting schedule of at least 70 trains and hitting road traffic adversely while there was no let up in cold wave on Saturday which claimed five lives in Uttar Pradesh and two in Punjab.
The railways observed a week of Azadi ki Rail Gadi, from July 18-23, through 27 trains and 75 railway stations, across 24 states that are linked to the Indian freedom struggle.