A hand grenade and a threat letter were found outside the office of a well-known snacks maker in Bishnupur district of Manipur on Tuesday, police said.
The hand grenade was found around 6.30 am outside the office of Kangla Food at Nambol, they said.
The staffers of the company immediately informed the police who seized the hand grenade.
The note, which was found, said "no more warning after this" and "we have been waiting for your calls for many months", police said.
The threat was related to extortion, they said, adding that a case was registered and an investigation started.