File photo of social activist Anna Hazare
Activist Anna Hazare has received a threat letter saying he would be "bumped off" if he does not dissociate himself from Delhi Chief Minister Arvind Kejriwal.
"The letter is dated August 7 and is mostly written in English," a police official told the Press Trust of India.
The letter warns that Mr Hazare, 78, will meet the same fate as rationalist Narendra Dabholkar who was shot dead near his home in Pune in 2013. It also asks the Gandhian to stay put in his native village of Ralegan Siddhi in Maharashtra, police said.
A case has been registered under Section 506 (criminal intimidation) of the Indian Penal Code at the Parner police station in Ahmednagar district, the police official said.