Superintendent of Police Neelkanta Sudhir Kumar said all the 21 police stations and nine check posts of the district were alerted after the posters were found pasted on trees near Chhoto Urma railway station, about 30 km from Purulia town.
In the posters, the PLGA urged people to join the organisation and denounced the central and state governments, the SP said.
The police have taken the posters away.