A group of prominent civil society members, including retired judges, bureaucrats and veterans, wrote to Prime Minister Narendra Modi on Saturday over the Odisha train tragedy, raising concerns over efforts to "undermine" India's national security and progress.

The letter has been signed by 270 signatories.

"We are greatly disturbed by the tragedy that has taken place in Balasore, Orissa involving our rapidly growing and modernizing Railways. Although investigation is still underway, as per initial media reports, there are reasons to suspect that the cause of the derailment could be deliberate human interference, a clear case of sabotage at the behest of terrorist outfits," they have said in the letter.

The letter said some of the signatories have worked in Jammu and Kashmir and in the northeast where they faced such situations of sabotage on the smooth plying on the railway network.

"There were similar well-planned attempts by terrorists to disrupt railway networks in these vulnerable areas, leading to sabotage, derailment and civilian casualties. In one of the many cases, J&K witnessed multiple attacks on railway lines from Pathankot to Jammu in 1990s and early 2000s where the tracks were severely damaged. 8 Catastrophic accidents stopped only after proper deployment was made," the letter stated.

Calling the Indian Railways "the lifeline of transport of goods and humans alike", the signatories alleged that forces inimical to the country's progress would like the network disrupted and create a catastrophe with massive human tragedy.

"Our view is that our entire Railway network is vulnerable and is particularly so in Eastern and Northeastern States, including the so-called 'Chicken's Neck'. It is imperative that illegal squatters, along railway tracks, including illegal immigrants be removed and stringent measures be taken to secure the safety of our railway tracks," the letter said.

The signatories include 14 former judges, 115 retired bureaucrats (11 ambassadors), 141 veterans.

Some of them are: Former Rajasthan High Court chief justice Anil Deo Singh, former Gujarat High Court judge S M Soni, former Uttar Pradesh DGP Vikram Singh, former Maharashtra DGP Praveen Dixit, former J&K police chief S P Vaid and former CBI director Nageshwar Rao.

Former defence secretary and secretary general Rajya Sabha Yogendra Narain, former RAW chief Sanjeev Tripathi and former NIA director Yogesh Chander Modi are also among the signatories.

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