The poster having signatures of People's Liberation Front of India (PLFI) commanders Minu Yadav and Suleman was found pasted on the signboard of Ratu police station, they said.
It threatened "severe punishment against corrupt officials and contractors".
A similar poster was also spotted at Kathitand Chowk, police said.
Dismissing the posters as a handiwork of some mischievous elements, SSP S S Singh said police were trying to identify the miscreants.