The posters were pasted by a unknown "Gramin Ekta Manch" organization, police said.
We have recovered an anti-naxal poster from Bakrapol and began investigation, said Deputy Superintendent of Police (Musaboni), Bachandeo Kujjur.
The posters allegedly warned the maoists to face sendra (lynching) if they dare to indulge in naxal activities in the Ghatsila sub-division.
When asked in this regard, Senior Superintendent Police, Amol V Homkar said the issue was being investigated.
The posters was detected two days after a fierce encounter between the security personnel and maoists at Chikam village bordering West Bengal on Wednesday.