"The PCAPA have left two posters near the rail tracks clearly owning responsibility for the derailment of the Kurla-bound Gyaneswari Express," IGP (Law and Order) S Karpurakayastha said.
The posters read, "We earlier demanded withdrawal of the joint security forces from Jangalmahal (West Midnapore, Bankura and Purulia) and end of CPI(M) atrocities, but those demands were not met."
Another poster demanded immediate withdrawal of the joint forces from the area.
Police have seized both posters.
On October 27 last year, the PCPA had detained the Bhubaneswar-New Delhi Rajdhani Express for eight hours during a bandh called by the outfit.
Nearly 400 villagers owing allegiance to the PCPA had blocked the Delhi-bound Rajdhani Express at Banstala halt in Jhargram.
The blockade was enforced as part of an indefinite bandh in the district to protest security force operations in the area.
