The Chennai Press Club on Wednesday received an anonymous letter, ending with the acronym "ISIS", warning of killing 10 Rashtriya Swamsevak Sangh (RSS) members and also carrying out serial bomb blasts here by April 24, a club official said.
Confirming the receipt of the warning letter, a press club official told IANS that the letter has been handed over to police.
"Identified 50 RSS active terrorists in Chennai. We swear to shoot at least 10 of them and repeat Kovai blasts by April 24," said the letter typed in red.
A similar letter is said to be received at the office of director general of police Tamil Nadu.
Police have launched an investigation on the matter.
The letter comes following the recent arrest of former Al-Umma activist Mannady Abdullah in connection with the murder of a Hindu Munnani functionary last year.
Several Muslim parties and organisations had condemned the arrest.