The father of a BJP activist, who was found hanging from a tree in West Bengal's Purulia district, filed a writ petition before the Calcutta High Court on Monday, seeking a CBI probe into the death.

Claiming that Trilochan Mahato was murdered for "political reason", his father Hariram said a "free and fair probe" would be possible only if the probe was carried out by the Central Bureau of Investigation (CBI).

Hariram Mahato's lawyer Priyanka Tibrewal said the petitioner, in his claim, has said the state police would find it difficult to conduct a fair probe into the incident owing to "political pressure".

"The writ petition is likely to be taken up for hearing before the court of Justice Tapabrata Chakraborty later this week," she said.

On May 30, the body of 18-year-old Trilochan Mahato was found hanging from a tree near his home at Balarampur in Purulia district, about 300 km from here.

An unsigned handwritten note in Bengali, which was slung around his neck, read that he was "punished for working for the BJP" during the recent panchayat elections in the state.

"Because you were involved with the BJP even at the age of 18, it claimed your life. I have been searching for you since the panchayat elections now you are dead," the note read.

Three days after Mahato's death, 35-year-old Dulal Kumar was found hanging from a power transmission tower in the same district. The BJP claimed that like Mahato, Kumar was also its worker.

The saffron party had been organising demonstrations and rallies in different parts of the state demanding justice for both Mahato and Kumar.