Four Sri Lankan Tamil refugees, including a pregnant woman, who arrived off Dhanushkodi coast here by an illegal ferry service on Thursday were arrested.
The refugees reached Arichalmunai near Dhanushkodi from Sri Lanka by paying Rs 30,000 as ferry charge, marine police said.
The refugees confessed that they had come for medical treatment.
Police said they were arrested under the Passport Act.
The investigation is on, they added.
On February 5, an 18-feet long Sri Lankan boat was found abandoned at Kambipaadu off Dhanushkodi coast with police suspecting the arrival of atleast six persons, either smugglers or illegal immigrants, by it.