DSP Vijayakumar said the refugees had arrived at Arichalmunai near Dhanushkodi from Sri Lanka and police with the help of the Coast Guard managed to nab a person, Santhan, who confessed that he had come along with some others by paying Rs one lakh as ferry charge.
Others are absconding, police said.
An official said they were interrogating Santhan, but were not sure how many had arrived with him.
Police said they had launched a massive hunt for other refugees as they suspected that they could be Sri Lankan militants.