Hailing from Mullaitheevu in Sri Lanka, they had landed by boat at Arisalmunai islet that day without visa or passports.
They were arrested from Dhanushkodi town the same day after they were found wandering about and sent to a special camp at Seiyarru and later to the Puzhal prison in Chennai.
All of them were produced before Judicial Magistrate G N Saravanakumar today, who convicted them under the Passport Act and sentenced to one-year imprisonment, police said.