Makkal Viduthalai Katchi members, led by party founder and former MLA Murugavel Rajan were waiting to board boats to the Katchatheevu islet after a rally from the Municipality office to the sea coast when they were arrested, they said.
The activists earlier burnt an effigy of Sri Lankan President Mahinda Rajapakse in protest against continued attacks on Indian fishermen, allegedly by naval personnel of the island nation.
They alleged that over 550 fishermen had been killed over time and the only solution was to retrieve Katchatheevu.
Murugavelrajan condemned Sri Lankan Minister Douglas Devanandha for his threat to mobilise Sri Lankan fisherman and hold a rally in mid sea off Rameswaram coast and for charging Indian fishermen with violating the IMBL and demanding that ministers from Tamil Nadu hold talks with them at Katchativu.
The party demanded that India support the US Backed resolution against Sri Lanka for violating Humanrights in the United Nations.
Athi Tamizhagar party leader ST Kalyanasundram also joined the former MLA. Party volunteers with the tricolour got into the sea, but were arrested, police said.