Chennai, Jan 9: The MDMK and the PMK said Friday that outgoing Sri Lankan president Mahinda Rajapaksa must be tried for war crimes.
MDMK general secretary Vaiko also urged president-elect Maithripala Sirisena to free all Tamils from prisons.
Tamil Nadu's political parties along with rights groups have accused Rajapaksa of killing thousands of Tamils in the end stages of the war that destroyed the Tamil Tigers in May 2009.
PMK founder S. Ramadoss said he was happy Sri Lankans had "punished" Rajapaksa by defeating him.
He said opposition candidate Sirisena won mainly due to the overwhelming support he got from Tamils.
Ramadoss also said that Rajapaksa should be tried for war crimes.
Both Vaiko and Ramadoss have been long time supporters of the Liberation Tigers of Tamil Eelam (LTTE) whose leadership was wiped out in 2009.
According to M.H. Jawahirullah, a legislator from the Manithaneya Makkal Katchi (MMK), Rajapaksa's defeat should be a warning to all autocrats.
"It is happy news that Rajapaksa has been defeated and that minorities in the country played a major role in that," he said.
"Rajapaksa's defeat is a warning to all those wanting to install an autocratic rule in a democratic country."