Soft spoken Ramesh, 52, a practicing chartered accountant, was killed near his office in Salem at around 10 p.m. by unknown assailants.
Condemning the killing, BJP state leader Pon Radhakrishnan told IANS: "The party has called for a state wide general strike Monday. Ramesh was a patriot and did not have any professional enemies. He is the fourth Hindu leader to be killed within a year."
Radhakrishnan said Ramesh had escaped an earlier attack on his life and his car was burnt.
"There is a concerted attack on Hindu leaders in the state and the government is not taking any serious action to put an end to this. Last month Hindu Munnani state secretary Vellaiayappan was murdered in the state," Radhakrishnan added.
He said there was no policeman at the murder spot when he visited it at around 4.30-5 a.m. Saturday.
"The murder evidence could have been erased," he remarked.
K.T. Raghavan, a spokesperson of state BJP, said: "There seems to be a concerted targeting of second line leadership of Hindu organisations in the state."
"BJP's medical wing secretary V. Aravind was killed in Vellore in 2012. Recently Hindu Munnani leader Vellaiappan was killed. The police seems to be having no clue about the killers," Raghavan told IANS.
Radhakrishnan said BJP leader Venkaiah Naidu will be going to Salem, about 335 km from here, to pay his respects.
"Gujarat Chief Minister Narendra Modi, party leader Arun Jaitely and others spoke to me and asked about the details," Radhakrishnan said.
Ramesh was twice the general secretary of the Tamil Nadu BJP and was also a trustee at the Chennai Port Trust.
He is survived by his wife Subha and daughter who studies in class 11.