The banned Hynniewtrep National Liberation Council (HNLC) also asked party workers to immediately resign from the NPP within a month’s time.
One 51 inch para-mortar bomb was found at Tuinom village, Churachandpur district on June 13 by some villagers in the jungle while searching for mushrooms.
A team of Lamphel police station along with bomb squad rush at the spot and retrieved the grenade.
A bomb blast occurred on February 27 at around 6:55 pm at De Khunai Resort, a lodging hotel which is owned by the MCM president.
Some miscreants hurled a hand grenade at Manipur's Raj Bhavan in Imphal on Tuesday
The police and AR team found the explosive during a cordon search in Kongba Bazar area at 10 am Monday.
The former minister said that this is the sixth time he was being threatened.