The deceased, Ravichandran, residing at Sirkali came out of his house on Friday night, doused himself with kerosene and set himself ablaze, shouting pro-Sri Lankan Tamil slogans.
He was rushed to Mayiladuthurai government hospital, where he succumbed to his burns on Saturday, the police said.
This is the second such incident to be reported in Tamil Nadu after the self-immolation of K Muthukumaran in Chennai recently.
Tension prevailed at the hospital in Nagapattinam when the Congress workers clashed with the activists of the recently floated Sri Lankan Tamils Protection Movement, comprising of the Pattali Makkal Katchi, the Marumalarchi Dravida Munnetra Kazhagam, the Communist Party of India, the Viduthalai Chiruthaigal Katchi and other fringe groups.
However, the police intervened and brought the situation under control. The Congress Member of Legislative Assembly from Mayiladuthurai, S Rajkumar, said that Ravichandran's mother was an activist of his party. Ravichandran, an unemployed, had recently joined the Congress, he told PTI in Nagapattinam.