A threat letter warning of "befitting reply" to Kerala Chief Minister Pinarayi Vijayan over the killing of seven Maoists in alleged encounters since 2016 has been received at a police station near here, police said on Friday.
The letter in Malayalam, signed by Bedar Moosa of a Maoist outfit, was received by post at the Vatakara police station and investigations were on, a senior police official said.
The threat comes in the backdrop of recent killing of four suspected Maoists in an alleged encounter with Kerala's specialised Thunderbolt police in a forest area near Attapady in Palakkad district.
"Yes, we have received a threat letter. It was sent from a nearby area. We have started the investigation," the official told PTI.
While opposition parties have raised doubts over the police version of encounter, Vijayan has strongly defended the action.
"Befitting reply will be given to the Chief Minister for gunning down seven comrades...," it said.
The letter also threatened a sub-inspector of police, saying he was "dangerous" to the state.
The police have already tightened security for the Chief Minister after four Maoists were killed in an exchange of fire during a two-day police combing operation in Palakkad district that started on October 28.
Maoist C P Jaleel was killed earlier this year in Wayanad while two other ultras were gunned down in 2017.