Police are maintaining tight vigil in the district in view of Prime Minister Narendra Modi's visit to inaugurate the memorial of former President A P J Abdul Kalam at Rameswaram on July 27.
Police, who got suspicious about his movements at Erwadi where he is staying in a lodge, found that he had come about a month ago.
Kasim Bai (60), hailing from Ul Bandal Street in Colombo, was arrested for allegedly entering the country without any valid documents, police said.
However, police said he was giving contradictory replies to various questions including purpose of his visit, and suspected that he could have come by an illegal ferry.